implement private members, fixes #74

test/codegen/expect/collection/collection.js

Index: test/codegen/expect/collection/collection.js
diff --git a/test/codegen/expect/collection/collection.js b/test/codegen/expect/collection/collection.js
index 0a1ec4153fdd10071edbbacfa6451e86d1ff05f8..8645fe3aef5c321cc76f5bbdc8d0dc8f851932ba 100644
--- a/test/codegen/expect/collection/collection.js
+++ b/test/codegen/expect/collection/collection.js
@@ -1,20 +1,42 @@
 var collection;
 (function(exports) {
   'use strict';
+  let _length = Symbol('_length');
+  let _strings = Symbol('_strings');
+  let _nums = Symbol('_nums');
+  let _rest = Symbol('_rest');
+  let _keys = Symbol('_keys');
+  let _containsKey = Symbol('_containsKey');
+  let _getBucket = Symbol('_getBucket');
+  let _findBucketIndex = Symbol('_findBucketIndex');
+  let _computeKeys = Symbol('_computeKeys');
+  let _get = Symbol('_get');
+  let _addHashTableEntry = Symbol('_addHashTableEntry');
+  let _set = Symbol('_set');
+  let _computeHashCode = Symbol('_computeHashCode');
+  let _removeHashTableEntry = Symbol('_removeHashTableEntry');
+  let _remove = Symbol('_remove');
+  let _isStringKey = Symbol('_isStringKey');
+  let _isNumericKey = Symbol('_isNumericKey');
+  let _hasTableEntry = Symbol('_hasTableEntry');
+  let _getTableEntry = Symbol('_getTableEntry');
+  let _setTableEntry = Symbol('_setTableEntry');
+  let _deleteTableEntry = Symbol('_deleteTableEntry');
+  let _newHashTable = Symbol('_newHashTable');
   let _HashMap$ = dart.generic(function(K, V) {
     class _HashMap extends dart.Object {
       _HashMap() {
-        this._length = 0;
-        this._strings = null;
-        this._nums = null;
-        this._rest = null;
-        this._keys = null;
+        this[_length] = 0;
+        this[_strings] = null;
+        this[_nums] = null;
+        this[_rest] = null;
+        this[_keys] = null;
       }
       get length() {
-        return this._length;
+        return this[_length];
       }
       get isEmpty() {
-        return this._length === 0;
+        return this[_length] === 0;
       }
       get isNotEmpty() {
         return !dart.notNull(this.isEmpty);
@@ -27,24 +49,24 @@ var collection;
       }
       containsKey(key) {
         if (_isStringKey(key)) {
-          let strings = this._strings;
+          let strings = this[_strings];
           return strings === null ? false : _hasTableEntry(strings, key);
         } else if (_isNumericKey(key)) {
-          let nums = this._nums;
+          let nums = this[_nums];
           return nums === null ? false : _hasTableEntry(nums, key);
         } else {
-          return this._containsKey(key);
+          return this[_containsKey](key);
         }
       }
-      _containsKey(key) {
-        let rest = this._rest;
+      [_containsKey](key) {
+        let rest = this[_rest];
         if (rest === null)
           return false;
-        let bucket = this._getBucket(rest, key);
-        return this._findBucketIndex(bucket, key) >= 0;
+        let bucket = this[_getBucket](rest, key);
+        return this[_findBucketIndex](bucket, key) >= 0;
       }
       containsValue(value) {
-        return this._computeKeys().any(((each) => dart.equals(this.get(each), value)).bind(this));
+        return this[_computeKeys]().any(((each) => dart.equals(this.get(each), value)).bind(this));
       }
       addAll(other) {
         other.forEach(((key, value) => {
@@ -53,56 +75,56 @@ var collection;
       }
       get(key) {
         if (_isStringKey(key)) {
-          let strings = this._strings;
+          let strings = this[_strings];
           return dart.as(strings === null ? null : _getTableEntry(strings, key), V);
         } else if (_isNumericKey(key)) {
-          let nums = this._nums;
+          let nums = this[_nums];
           return dart.as(nums === null ? null : _getTableEntry(nums, key), V);
         } else {
-          return this._get(key);
+          return this[_get](key);
         }
       }
-      _get(key) {
-        let rest = this._rest;
+      [_get](key) {
+        let rest = this[_rest];
         if (rest === null)
           return dart.as(null, V);
-        let bucket = this._getBucket(rest, key);
-        let index = this._findBucketIndex(bucket, key);
+        let bucket = this[_getBucket](rest, key);
+        let index = this[_findBucketIndex](bucket, key);
         return dart.as(index < 0 ? null : bucket[index + 1], V);
       }
       set(key, value) {
         if (_isStringKey(key)) {
-          let strings = this._strings;
+          let strings = this[_strings];
           if (strings === null)
-            this._strings = strings = _newHashTable();
-          this._addHashTableEntry(strings, key, value);
+            this[_strings] = strings = _newHashTable();
+          this[_addHashTableEntry](strings, key, value);
         } else if (_isNumericKey(key)) {
-          let nums = this._nums;
+          let nums = this[_nums];
           if (nums === null)
-            this._nums = nums = _newHashTable();
-          this._addHashTableEntry(nums, key, value);
+            this[_nums] = nums = _newHashTable();
+          this[_addHashTableEntry](nums, key, value);
         } else {
-          this._set(key, value);
+          this[_set](key, value);
         }
       }
-      _set(key, value) {
-        let rest = this._rest;
+      [_set](key, value) {
+        let rest = this[_rest];
         if (rest === null)
-          this._rest = rest = _newHashTable();
-        let hash = this._computeHashCode(key);
+          this[_rest] = rest = _newHashTable();
+        let hash = this[_computeHashCode](key);
         let bucket = rest[hash];
         if (bucket === null) {
           _setTableEntry(rest, hash, [key, value]);
-          this._length++;
-          this._keys = null;
+          this[_length]++;
+          this[_keys] = null;
         } else {
-          let index = this._findBucketIndex(bucket, key);
+          let index = this[_findBucketIndex](bucket, key);
           if (index >= 0) {
             bucket[index + 1] = value;
           } else {
             bucket.push(key, value);
-            this._length++;
-            this._keys = null;
+            this[_length]++;
+            this[_keys] = null;
           }
         }
       }
@@ -115,47 +137,47 @@ var collection;
       }
       remove(key) {
         if (_isStringKey(key)) {
-          return this._removeHashTableEntry(this._strings, key);
+          return this[_removeHashTableEntry](this[_strings], key);
         } else if (_isNumericKey(key)) {
-          return this._removeHashTableEntry(this._nums, key);
+          return this[_removeHashTableEntry](this[_nums], key);
         } else {
-          return this._remove(key);
+          return this[_remove](key);
         }
       }
-      _remove(key) {
-        let rest = this._rest;
+      [_remove](key) {
+        let rest = this[_rest];
         if (rest === null)
           return dart.as(null, V);
-        let bucket = this._getBucket(rest, key);
-        let index = this._findBucketIndex(bucket, key);
+        let bucket = this[_getBucket](rest, key);
+        let index = this[_findBucketIndex](bucket, key);
         if (index < 0)
           return dart.as(null, V);
-        this._length--;
-        this._keys = null;
+        this[_length]--;
+        this[_keys] = null;
         return dart.as(bucket.splice(index, 2)[1], V);
       }
       clear() {
-        if (this._length > 0) {
-          this._strings = this._nums = this._rest = this._keys = null;
-          this._length = 0;
+        if (this[_length] > 0) {
+          this[_strings] = this[_nums] = this[_rest] = this[_keys] = null;
+          this[_length] = 0;
         }
       }
       forEach(action) {
-        let keys = this._computeKeys();
+        let keys = this[_computeKeys]();
         for (let i = 0, length = keys.length; i < length; i++) {
           let key = keys[i];
           action(dart.as(key, K), this.get(key));
-          if (keys !== this._keys) {
+          if (keys !== this[_keys]) {
             throw new core.ConcurrentModificationError(this);
           }
         }
       }
-      _computeKeys() {
-        if (this._keys !== null)
-          return this._keys;
-        let result = new core.List(this._length);
+      [_computeKeys]() {
+        if (this[_keys] !== null)
+          return this[_keys];
+        let result = new core.List(this[_length]);
         let index = 0;
-        let strings = this._strings;
+        let strings = this[_strings];
         if (strings !== null) {
           let names = Object.getOwnPropertyNames(strings);
           let entries = names.length;
@@ -165,7 +187,7 @@ var collection;
             index++;
           }
         }
-        let nums = this._nums;
+        let nums = this[_nums];
         if (nums !== null) {
           let names = Object.getOwnPropertyNames(nums);
           let entries = names.length;
@@ -175,7 +197,7 @@ var collection;
             index++;
           }
         }
-        let rest = this._rest;
+        let rest = this[_rest];
         if (rest !== null) {
           let names = Object.getOwnPropertyNames(rest);
           let entries = names.length;
@@ -190,59 +212,59 @@ var collection;
             }
           }
         }
-        dart.assert(index === this._length);
-        return this._keys = result;
+        dart.assert(index === this[_length]);
+        return this[_keys] = result;
       }
-      _addHashTableEntry(table, key, value) {
+      [_addHashTableEntry](table, key, value) {
         if (!dart.notNull(_hasTableEntry(table, key))) {
-          this._length++;
-          this._keys = null;
+          this[_length]++;
+          this[_keys] = null;
         }
         _setTableEntry(table, key, value);
       }
-      _removeHashTableEntry(table, key) {
+      [_removeHashTableEntry](table, key) {
         if (dart.notNull(table !== null) && dart.notNull(_hasTableEntry(table, key))) {
           let value = dart.as(_getTableEntry(table, key), V);
           _deleteTableEntry(table, key);
-          this._length--;
-          this._keys = null;
+          this[_length]--;
+          this[_keys] = null;
           return value;
         } else {
           return dart.as(null, V);
         }
       }
-      static _isStringKey(key) {
+      static [_isStringKey](key) {
         return dart.notNull(typeof key == string) && dart.notNull(!dart.equals(key, '__proto__'));
       }
-      static _isNumericKey(key) {
+      static [_isNumericKey](key) {
         return dart.notNull(dart.is(key, core.num)) && dart.notNull((key & 0x3ffffff) === key);
       }
-      _computeHashCode(key) {
+      [_computeHashCode](key) {
         return dart.dload(key, 'hashCode') & 0x3ffffff;
       }
-      static _hasTableEntry(table, key) {
+      static [_hasTableEntry](table, key) {
         let entry = table[key];
         return entry !== null;
       }
-      static _getTableEntry(table, key) {
+      static [_getTableEntry](table, key) {
         let entry = table[key];
         return entry === table ? null : entry;
       }
-      static _setTableEntry(table, key, value) {
+      static [_setTableEntry](table, key, value) {
         if (value === null) {
           table[key] = table;
         } else {
           table[key] = value;
         }
       }
-      static _deleteTableEntry(table, key) {
+      static [_deleteTableEntry](table, key) {
         delete table[key];
       }
-      _getBucket(table, key) {
-        let hash = this._computeHashCode(key);
+      [_getBucket](table, key) {
+        let hash = this[_computeHashCode](key);
         return dart.as(table[hash], core.List);
       }
-      _findBucketIndex(bucket, key) {
+      [_findBucketIndex](bucket, key) {
         if (bucket === null)
           return -1;
         let length = bucket.length;
@@ -252,7 +274,7 @@ var collection;
         }
         return -1;
       }
-      static _newHashTable() {
+      static [_newHashTable]() {
         let table = Object.create(null);
         let temporaryKey = '<non-identifier-key>';
         _setTableEntry(table, temporaryKey, table);
@@ -265,10 +287,10 @@ var collection;
   let _HashMap = _HashMap$(dynamic, dynamic);
   let _IdentityHashMap$ = dart.generic(function(K, V) {
     class _IdentityHashMap extends _HashMap$(K, V) {
-      _computeHashCode(key) {
+      [_computeHashCode](key) {
         return core.identityHashCode(key) & 0x3ffffff;
       }
-      _findBucketIndex(bucket, key) {
+      [_findBucketIndex](bucket, key) {
         if (bucket === null)
           return -1;
         let length = bucket.length;
@@ -282,16 +304,19 @@ var collection;
     return _IdentityHashMap;
   });
   let _IdentityHashMap = _IdentityHashMap$(dynamic, dynamic);
+  let _equals = Symbol('_equals');
+  let _hashCode = Symbol('_hashCode');
+  let _validKey = Symbol('_validKey');
   let _CustomHashMap$ = dart.generic(function(K, V) {
     class _CustomHashMap extends _HashMap$(K, V) {
-      _CustomHashMap(_equals, _hashCode, validKey) {
-        this._equals = _equals;
-        this._hashCode = _hashCode;
-        this._validKey = dart.as(validKey !== null ? validKey : (v) => dart.is(v, K), _Predicate);
+      _CustomHashMap($_equals, $_hashCode, validKey) {
+        this[_equals] = $_equals;
+        this[_hashCode] = $_hashCode;
+        this[_validKey] = dart.as(validKey !== null ? validKey : (v) => dart.is(v, K), _Predicate);
         super._HashMap();
       }
       get(key) {
-        if (!dart.notNull(this._validKey(key)))
+        if (!dart.notNull(this[_validKey](key)))
           return dart.as(null, V);
         return super._get(key);
       }
@@ -299,24 +324,24 @@ var collection;
         super._set(key, value);
       }
       containsKey(key) {
-        if (!dart.notNull(this._validKey(key)))
+        if (!dart.notNull(this[_validKey](key)))
           return false;
         return super._containsKey(key);
       }
       remove(key) {
-        if (!dart.notNull(this._validKey(key)))
+        if (!dart.notNull(this[_validKey](key)))
           return dart.as(null, V);
         return super._remove(key);
       }
-      _computeHashCode(key) {
-        return this._hashCode(dart.as(key, K)) & 0x3ffffff;
+      [_computeHashCode](key) {
+        return this[_hashCode](dart.as(key, K)) & 0x3ffffff;
       }
-      _findBucketIndex(bucket, key) {
+      [_findBucketIndex](bucket, key) {
         if (bucket === null)
           return -1;
         let length = bucket.length;
         for (let i = 0; i < length; i = 2) {
-          if (this._equals(dart.as(bucket[i], K), dart.as(key, K)))
+          if (this[_equals](dart.as(bucket[i], K), dart.as(key, K)))
             return i;
         }
         return -1;
@@ -328,30 +353,31 @@ var collection;
     return _CustomHashMap;
   });
   let _CustomHashMap = _CustomHashMap$(dynamic, dynamic);
+  let _map = Symbol('_map');
   let HashMapKeyIterable$ = dart.generic(function(E) {
     class HashMapKeyIterable extends IterableBase$(E) {
-      HashMapKeyIterable(_map) {
-        this._map = _map;
+      HashMapKeyIterable($_map) {
+        this[_map] = $_map;
         super.IterableBase();
       }
       get length() {
-        return dart.as(dart.dload(this._map, '_length'), core.int);
+        return dart.as(dart.dload(this[_map], '_length'), core.int);
       }
       get isEmpty() {
-        return dart.equals(dart.dload(this._map, '_length'), 0);
+        return dart.equals(dart.dload(this[_map], '_length'), 0);
       }
       get iterator() {
-        return new HashMapKeyIterator(this._map, dart.as(dart.dinvoke(this._map, '_computeKeys'), core.List));
+        return new HashMapKeyIterator(this[_map], dart.as(dart.dinvoke(this[_map], '_computeKeys'), core.List));
       }
       contains(element) {
-        return dart.as(dart.dinvoke(this._map, 'containsKey', element), core.bool);
+        return dart.as(dart.dinvoke(this[_map], 'containsKey', element), core.bool);
       }
       forEach(f) {
-        let keys = dart.as(dart.dinvoke(this._map, '_computeKeys'), core.List);
+        let keys = dart.as(dart.dinvoke(this[_map], '_computeKeys'), core.List);
         for (let i = 0, length = keys.length; i < length; i++) {
           f(dart.as(keys[i], E));
-          if (keys !== dart.dload(this._map, '_keys')) {
-            throw new core.ConcurrentModificationError(this._map);
+          if (keys !== dart.dload(this[_map], '_keys')) {
+            throw new core.ConcurrentModificationError(this[_map]);
           }
         }
       }
@@ -359,28 +385,30 @@ var collection;
     return HashMapKeyIterable;
   });
   let HashMapKeyIterable = HashMapKeyIterable$(dynamic);
+  let _offset = Symbol('_offset');
+  let _current = Symbol('_current');
   let HashMapKeyIterator$ = dart.generic(function(E) {
     class HashMapKeyIterator extends dart.Object {
-      HashMapKeyIterator(_map, _keys) {
-        this._map = _map;
-        this._keys = _keys;
-        this._offset = 0;
-        this._current = dart.as(null, E);
+      HashMapKeyIterator($_map, $_keys) {
+        this[_map] = $_map;
+        this[_keys] = $_keys;
+        this[_offset] = 0;
+        this[_current] = dart.as(null, E);
       }
       get current() {
-        return this._current;
+        return this[_current];
       }
       moveNext() {
-        let keys = this._keys;
-        let offset = this._offset;
-        if (keys !== dart.dload(this._map, '_keys')) {
-          throw new core.ConcurrentModificationError(this._map);
+        let keys = this[_keys];
+        let offset = this[_offset];
+        if (keys !== dart.dload(this[_map], '_keys')) {
+          throw new core.ConcurrentModificationError(this[_map]);
         } else if (offset >= keys.length) {
-          this._current = dart.as(null, E);
+          this[_current] = dart.as(null, E);
           return false;
         } else {
-          this._current = dart.as(keys[offset], E);
-          this._offset = offset + 1;
+          this[_current] = dart.as(keys[offset], E);
+          this[_offset] = offset + 1;
           return true;
         }
       }
@@ -388,22 +416,32 @@ var collection;
     return HashMapKeyIterator;
   });
   let HashMapKeyIterator = HashMapKeyIterator$(dynamic);
+  let _first = Symbol('_first');
+  let _last = Symbol('_last');
+  let _modifications = Symbol('_modifications');
+  let _value = Symbol('_value');
+  let _newLinkedCell = Symbol('_newLinkedCell');
+  let _unlinkCell = Symbol('_unlinkCell');
+  let _modified = Symbol('_modified');
+  let _key = Symbol('_key');
+  let _next = Symbol('_next');
+  let _previous = Symbol('_previous');
   let _LinkedHashMap$ = dart.generic(function(K, V) {
     class _LinkedHashMap extends dart.Object {
       _LinkedHashMap() {
-        this._length = 0;
-        this._strings = null;
-        this._nums = null;
-        this._rest = null;
-        this._first = null;
-        this._last = null;
-        this._modifications = 0;
+        this[_length] = 0;
+        this[_strings] = null;
+        this[_nums] = null;
+        this[_rest] = null;
+        this[_first] = null;
+        this[_last] = null;
+        this[_modifications] = 0;
       }
       get length() {
-        return this._length;
+        return this[_length];
       }
       get isEmpty() {
-        return this._length === 0;
+        return this[_length] === 0;
       }
       get isNotEmpty() {
         return !dart.notNull(this.isEmpty);
@@ -416,27 +454,27 @@ var collection;
       }
       containsKey(key) {
         if (_isStringKey(key)) {
-          let strings = this._strings;
+          let strings = this[_strings];
           if (strings === null)
             return false;
           let cell = dart.as(_getTableEntry(strings, key), LinkedHashMapCell);
           return cell !== null;
         } else if (_isNumericKey(key)) {
-          let nums = this._nums;
+          let nums = this[_nums];
           if (nums === null)
             return false;
           let cell = dart.as(_getTableEntry(nums, key), LinkedHashMapCell);
           return cell !== null;
         } else {
-          return this._containsKey(key);
+          return this[_containsKey](key);
         }
       }
-      _containsKey(key) {
-        let rest = this._rest;
+      [_containsKey](key) {
+        let rest = this[_rest];
         if (rest === null)
           return false;
-        let bucket = this._getBucket(rest, key);
-        return this._findBucketIndex(bucket, key) >= 0;
+        let bucket = this[_getBucket](rest, key);
+        return this[_findBucketIndex](bucket, key) >= 0;
       }
       containsValue(value) {
         return this.keys.any(((each) => dart.equals(this.get(each), value)).bind(this));
@@ -448,63 +486,63 @@ var collection;
       }
       get(key) {
         if (_isStringKey(key)) {
-          let strings = this._strings;
+          let strings = this[_strings];
           if (strings === null)
             return dart.as(null, V);
           let cell = dart.as(_getTableEntry(strings, key), LinkedHashMapCell);
-          return dart.as(cell === null ? null : cell._value, V);
+          return dart.as(cell === null ? null : cell[_value], V);
         } else if (_isNumericKey(key)) {
-          let nums = this._nums;
+          let nums = this[_nums];
           if (nums === null)
             return dart.as(null, V);
           let cell = dart.as(_getTableEntry(nums, key), LinkedHashMapCell);
-          return dart.as(cell === null ? null : cell._value, V);
+          return dart.as(cell === null ? null : cell[_value], V);
         } else {
-          return this._get(key);
+          return this[_get](key);
         }
       }
-      _get(key) {
-        let rest = this._rest;
+      [_get](key) {
+        let rest = this[_rest];
         if (rest === null)
           return dart.as(null, V);
-        let bucket = this._getBucket(rest, key);
-        let index = this._findBucketIndex(bucket, key);
+        let bucket = this[_getBucket](rest, key);
+        let index = this[_findBucketIndex](bucket, key);
         if (index < 0)
           return dart.as(null, V);
         let cell = dart.as(bucket[index], LinkedHashMapCell);
-        return dart.as(cell._value, V);
+        return dart.as(cell[_value], V);
       }
       set(key, value) {
         if (_isStringKey(key)) {
-          let strings = this._strings;
+          let strings = this[_strings];
           if (strings === null)
-            this._strings = strings = _newHashTable();
-          this._addHashTableEntry(strings, key, value);
+            this[_strings] = strings = _newHashTable();
+          this[_addHashTableEntry](strings, key, value);
         } else if (_isNumericKey(key)) {
-          let nums = this._nums;
+          let nums = this[_nums];
           if (nums === null)
-            this._nums = nums = _newHashTable();
-          this._addHashTableEntry(nums, key, value);
+            this[_nums] = nums = _newHashTable();
+          this[_addHashTableEntry](nums, key, value);
         } else {
-          this._set(key, value);
+          this[_set](key, value);
         }
       }
-      _set(key, value) {
-        let rest = this._rest;
+      [_set](key, value) {
+        let rest = this[_rest];
         if (rest === null)
-          this._rest = rest = _newHashTable();
-        let hash = this._computeHashCode(key);
+          this[_rest] = rest = _newHashTable();
+        let hash = this[_computeHashCode](key);
         let bucket = rest[hash];
         if (bucket === null) {
-          let cell = this._newLinkedCell(key, value);
+          let cell = this[_newLinkedCell](key, value);
           _setTableEntry(rest, hash, [cell]);
         } else {
-          let index = this._findBucketIndex(bucket, key);
+          let index = this[_findBucketIndex](bucket, key);
           if (index >= 0) {
             let cell = dart.as(bucket[index], LinkedHashMapCell);
-            cell._value = value;
+            cell[_value] = value;
           } else {
-            let cell = this._newLinkedCell(key, value);
+            let cell = this[_newLinkedCell](key, value);
             bucket.push(cell);
           }
         }
@@ -518,130 +556,130 @@ var collection;
       }
       remove(key) {
         if (_isStringKey(key)) {
-          return this._removeHashTableEntry(this._strings, key);
+          return this[_removeHashTableEntry](this[_strings], key);
         } else if (_isNumericKey(key)) {
-          return this._removeHashTableEntry(this._nums, key);
+          return this[_removeHashTableEntry](this[_nums], key);
         } else {
-          return this._remove(key);
+          return this[_remove](key);
         }
       }
-      _remove(key) {
-        let rest = this._rest;
+      [_remove](key) {
+        let rest = this[_rest];
         if (rest === null)
           return dart.as(null, V);
-        let bucket = this._getBucket(rest, key);
-        let index = this._findBucketIndex(bucket, key);
+        let bucket = this[_getBucket](rest, key);
+        let index = this[_findBucketIndex](bucket, key);
         if (index < 0)
           return dart.as(null, V);
         let cell = dart.as(bucket.splice(index, 1)[0], LinkedHashMapCell);
-        this._unlinkCell(cell);
-        return dart.as(cell._value, V);
+        this[_unlinkCell](cell);
+        return dart.as(cell[_value], V);
       }
       clear() {
-        if (this._length > 0) {
-          this._strings = this._nums = this._rest = this._first = this._last = null;
-          this._length = 0;
-          this._modified();
+        if (this[_length] > 0) {
+          this[_strings] = this[_nums] = this[_rest] = this[_first] = this[_last] = null;
+          this[_length] = 0;
+          this[_modified]();
         }
       }
       forEach(action) {
-        let cell = this._first;
-        let modifications = this._modifications;
+        let cell = this[_first];
+        let modifications = this[_modifications];
         while (cell !== null) {
-          action(dart.as(cell._key, K), dart.as(cell._value, V));
-          if (modifications !== this._modifications) {
+          action(dart.as(cell[_key], K), dart.as(cell[_value], V));
+          if (modifications !== this[_modifications]) {
             throw new core.ConcurrentModificationError(this);
           }
-          cell = cell._next;
+          cell = cell[_next];
         }
       }
-      _addHashTableEntry(table, key, value) {
+      [_addHashTableEntry](table, key, value) {
         let cell = dart.as(_getTableEntry(table, key), LinkedHashMapCell);
         if (cell === null) {
-          _setTableEntry(table, key, this._newLinkedCell(key, value));
+          _setTableEntry(table, key, this[_newLinkedCell](key, value));
         } else {
-          cell._value = value;
+          cell[_value] = value;
         }
       }
-      _removeHashTableEntry(table, key) {
+      [_removeHashTableEntry](table, key) {
         if (table === null)
           return dart.as(null, V);
         let cell = dart.as(_getTableEntry(table, key), LinkedHashMapCell);
         if (cell === null)
           return dart.as(null, V);
-        this._unlinkCell(cell);
+        this[_unlinkCell](cell);
         _deleteTableEntry(table, key);
-        return dart.as(cell._value, V);
+        return dart.as(cell[_value], V);
       }
-      _modified() {
-        this._modifications = this._modifications + 1 & 67108863;
+      [_modified]() {
+        this[_modifications] = this[_modifications] + 1 & 67108863;
       }
-      _newLinkedCell(key, value) {
+      [_newLinkedCell](key, value) {
         let cell = new LinkedHashMapCell(key, value);
-        if (this._first === null) {
-          this._first = this._last = cell;
+        if (this[_first] === null) {
+          this[_first] = this[_last] = cell;
         } else {
-          let last = this._last;
-          cell._previous = last;
-          this._last = last._next = cell;
+          let last = this[_last];
+          cell[_previous] = last;
+          this[_last] = last[_next] = cell;
         }
-        this._length++;
-        this._modified();
+        this[_length]++;
+        this[_modified]();
         return cell;
       }
-      _unlinkCell(cell) {
-        let previous = cell._previous;
-        let next = cell._next;
+      [_unlinkCell](cell) {
+        let previous = cell[_previous];
+        let next = cell[_next];
         if (previous === null) {
-          dart.assert(dart.equals(cell, this._first));
-          this._first = next;
+          dart.assert(dart.equals(cell, this[_first]));
+          this[_first] = next;
         } else {
-          previous._next = next;
+          previous[_next] = next;
         }
         if (next === null) {
-          dart.assert(dart.equals(cell, this._last));
-          this._last = previous;
+          dart.assert(dart.equals(cell, this[_last]));
+          this[_last] = previous;
         } else {
-          next._previous = previous;
+          next[_previous] = previous;
         }
-        this._length--;
-        this._modified();
+        this[_length]--;
+        this[_modified]();
       }
-      static _isStringKey(key) {
+      static [_isStringKey](key) {
         return dart.notNull(typeof key == string) && dart.notNull(!dart.equals(key, '__proto__'));
       }
-      static _isNumericKey(key) {
+      static [_isNumericKey](key) {
         return dart.notNull(dart.is(key, core.num)) && dart.notNull((key & 0x3ffffff) === key);
       }
-      _computeHashCode(key) {
+      [_computeHashCode](key) {
         return dart.dload(key, 'hashCode') & 0x3ffffff;
       }
-      static _getTableEntry(table, key) {
+      static [_getTableEntry](table, key) {
         return table[key];
       }
-      static _setTableEntry(table, key, value) {
+      static [_setTableEntry](table, key, value) {
         dart.assert(value !== null);
         table[key] = value;
       }
-      static _deleteTableEntry(table, key) {
+      static [_deleteTableEntry](table, key) {
         delete table[key];
       }
-      _getBucket(table, key) {
-        let hash = this._computeHashCode(key);
+      [_getBucket](table, key) {
+        let hash = this[_computeHashCode](key);
         return dart.as(table[hash], core.List);
       }
-      _findBucketIndex(bucket, key) {
+      [_findBucketIndex](bucket, key) {
         if (bucket === null)
           return -1;
         let length = bucket.length;
         for (let i = 0; i < length; i++) {
           let cell = dart.as(bucket[i], LinkedHashMapCell);
-          if (dart.equals(cell._key, key))
+          if (dart.equals(cell[_key], key))
             return i;
         }
         return -1;
       }
-      static _newHashTable() {
+      static [_newHashTable]() {
         let table = Object.create(null);
         let temporaryKey = '<non-identifier-key>';
         _setTableEntry(table, temporaryKey, table);
@@ -657,16 +695,16 @@ var collection;
   let _LinkedHashMap = _LinkedHashMap$(dynamic, dynamic);
   let _LinkedIdentityHashMap$ = dart.generic(function(K, V) {
     class _LinkedIdentityHashMap extends _LinkedHashMap$(K, V) {
-      _computeHashCode(key) {
+      [_computeHashCode](key) {
         return core.identityHashCode(key) & 0x3ffffff;
       }
-      _findBucketIndex(bucket, key) {
+      [_findBucketIndex](bucket, key) {
         if (bucket === null)
           return -1;
         let length = bucket.length;
         for (let i = 0; i < length; i++) {
           let cell = dart.as(bucket[i], LinkedHashMapCell);
-          if (core.identical(cell._key, key))
+          if (core.identical(cell[_key], key))
             return i;
         }
         return -1;
@@ -677,14 +715,14 @@ var collection;
   let _LinkedIdentityHashMap = _LinkedIdentityHashMap$(dynamic, dynamic);
   let _LinkedCustomHashMap$ = dart.generic(function(K, V) {
     class _LinkedCustomHashMap extends _LinkedHashMap$(K, V) {
-      _LinkedCustomHashMap(_equals, _hashCode, validKey) {
-        this._equals = _equals;
-        this._hashCode = _hashCode;
-        this._validKey = dart.as(validKey !== null ? validKey : (v) => dart.is(v, K), _Predicate);
+      _LinkedCustomHashMap($_equals, $_hashCode, validKey) {
+        this[_equals] = $_equals;
+        this[_hashCode] = $_hashCode;
+        this[_validKey] = dart.as(validKey !== null ? validKey : (v) => dart.is(v, K), _Predicate);
         super._LinkedHashMap();
       }
       get(key) {
-        if (!dart.notNull(this._validKey(key)))
+        if (!dart.notNull(this[_validKey](key)))
           return dart.as(null, V);
         return super._get(key);
       }
@@ -692,25 +730,25 @@ var collection;
         super._set(key, value);
       }
       containsKey(key) {
-        if (!dart.notNull(this._validKey(key)))
+        if (!dart.notNull(this[_validKey](key)))
           return false;
         return super._containsKey(key);
       }
       remove(key) {
-        if (!dart.notNull(this._validKey(key)))
+        if (!dart.notNull(this[_validKey](key)))
           return dart.as(null, V);
         return super._remove(key);
       }
-      _computeHashCode(key) {
-        return this._hashCode(dart.as(key, K)) & 0x3ffffff;
+      [_computeHashCode](key) {
+        return this[_hashCode](dart.as(key, K)) & 0x3ffffff;
       }
-      _findBucketIndex(bucket, key) {
+      [_findBucketIndex](bucket, key) {
         if (bucket === null)
           return -1;
         let length = bucket.length;
         for (let i = 0; i < length; i++) {
           let cell = dart.as(bucket[i], LinkedHashMapCell);
-          if (this._equals(dart.as(cell._key, K), dart.as(key, K)))
+          if (this[_equals](dart.as(cell[_key], K), dart.as(key, K)))
             return i;
         }
         return -1;
@@ -720,67 +758,68 @@ var collection;
   });
   let _LinkedCustomHashMap = _LinkedCustomHashMap$(dynamic, dynamic);
   class LinkedHashMapCell extends dart.Object {
-    LinkedHashMapCell(_key, _value) {
-      this._key = _key;
-      this._value = _value;
-      this._next = null;
-      this._previous = null;
+    LinkedHashMapCell($_key, $_value) {
+      this[_key] = $_key;
+      this[_value] = $_value;
+      this[_next] = null;
+      this[_previous] = null;
     }
   }
   let LinkedHashMapKeyIterable$ = dart.generic(function(E) {
     class LinkedHashMapKeyIterable extends IterableBase$(E) {
-      LinkedHashMapKeyIterable(_map) {
-        this._map = _map;
+      LinkedHashMapKeyIterable($_map) {
+        this[_map] = $_map;
         super.IterableBase();
       }
       get length() {
-        return dart.as(dart.dload(this._map, '_length'), core.int);
+        return dart.as(dart.dload(this[_map], '_length'), core.int);
       }
       get isEmpty() {
-        return dart.equals(dart.dload(this._map, '_length'), 0);
+        return dart.equals(dart.dload(this[_map], '_length'), 0);
       }
       get iterator() {
-        return new LinkedHashMapKeyIterator(this._map, dart.as(dart.dload(this._map, '_modifications'), core.int));
+        return new LinkedHashMapKeyIterator(this[_map], dart.as(dart.dload(this[_map], '_modifications'), core.int));
       }
       contains(element) {
-        return dart.as(dart.dinvoke(this._map, 'containsKey', element), core.bool);
+        return dart.as(dart.dinvoke(this[_map], 'containsKey', element), core.bool);
       }
       forEach(f) {
-        let cell = dart.as(dart.dload(this._map, '_first'), LinkedHashMapCell);
-        let modifications = dart.as(dart.dload(this._map, '_modifications'), core.int);
+        let cell = dart.as(dart.dload(this[_map], '_first'), LinkedHashMapCell);
+        let modifications = dart.as(dart.dload(this[_map], '_modifications'), core.int);
         while (cell !== null) {
-          f(dart.as(cell._key, E));
-          if (modifications !== dart.dload(this._map, '_modifications')) {
-            throw new core.ConcurrentModificationError(this._map);
+          f(dart.as(cell[_key], E));
+          if (modifications !== dart.dload(this[_map], '_modifications')) {
+            throw new core.ConcurrentModificationError(this[_map]);
           }
-          cell = cell._next;
+          cell = cell[_next];
         }
       }
     }
     return LinkedHashMapKeyIterable;
   });
   let LinkedHashMapKeyIterable = LinkedHashMapKeyIterable$(dynamic);
+  let _cell = Symbol('_cell');
   let LinkedHashMapKeyIterator$ = dart.generic(function(E) {
     class LinkedHashMapKeyIterator extends dart.Object {
-      LinkedHashMapKeyIterator(_map, _modifications) {
-        this._map = _map;
-        this._modifications = _modifications;
-        this._cell = null;
-        this._current = dart.as(null, E);
-        this._cell = dart.as(dart.dload(this._map, '_first'), LinkedHashMapCell);
+      LinkedHashMapKeyIterator($_map, $_modifications) {
+        this[_map] = $_map;
+        this[_modifications] = $_modifications;
+        this[_cell] = null;
+        this[_current] = dart.as(null, E);
+        this[_cell] = dart.as(dart.dload(this[_map], '_first'), LinkedHashMapCell);
       }
       get current() {
-        return this._current;
+        return this[_current];
       }
       moveNext() {
-        if (this._modifications !== dart.dload(this._map, '_modifications')) {
-          throw new core.ConcurrentModificationError(this._map);
-        } else if (this._cell === null) {
-          this._current = dart.as(null, E);
+        if (this[_modifications] !== dart.dload(this[_map], '_modifications')) {
+          throw new core.ConcurrentModificationError(this[_map]);
+        } else if (this[_cell] === null) {
+          this[_current] = dart.as(null, E);
           return false;
         } else {
-          this._current = dart.as(this._cell._key, E);
-          this._cell = this._cell._next;
+          this[_current] = dart.as(this[_cell][_key], E);
+          this[_cell] = this[_cell][_next];
           return true;
         }
       }
@@ -788,96 +827,104 @@ var collection;
     return LinkedHashMapKeyIterator;
   });
   let LinkedHashMapKeyIterator = LinkedHashMapKeyIterator$(dynamic);
+  let _elements = Symbol('_elements');
+  let _newSet = Symbol('_newSet');
+  let _computeElements = Symbol('_computeElements');
+  let _contains = Symbol('_contains');
+  let _lookup = Symbol('_lookup');
+  let _add = Symbol('_add');
+  let _isStringElement = Symbol('_isStringElement');
+  let _isNumericElement = Symbol('_isNumericElement');
   let _HashSet$ = dart.generic(function(E) {
     class _HashSet extends _HashSetBase$(E) {
       _HashSet() {
-        this._length = 0;
-        this._strings = null;
-        this._nums = null;
-        this._rest = null;
-        this._elements = null;
+        this[_length] = 0;
+        this[_strings] = null;
+        this[_nums] = null;
+        this[_rest] = null;
+        this[_elements] = null;
         super._HashSetBase();
       }
-      _newSet() {
+      [_newSet]() {
         return new _HashSet();
       }
       get iterator() {
-        return new HashSetIterator(this, this._computeElements());
+        return new HashSetIterator(this, this[_computeElements]());
       }
       get length() {
-        return this._length;
+        return this[_length];
       }
       get isEmpty() {
-        return this._length === 0;
+        return this[_length] === 0;
       }
       get isNotEmpty() {
         return !dart.notNull(this.isEmpty);
       }
       contains(object) {
         if (_isStringElement(object)) {
-          let strings = this._strings;
+          let strings = this[_strings];
           return strings === null ? false : _hasTableEntry(strings, object);
         } else if (_isNumericElement(object)) {
-          let nums = this._nums;
+          let nums = this[_nums];
           return nums === null ? false : _hasTableEntry(nums, object);
         } else {
-          return this._contains(object);
+          return this[_contains](object);
         }
       }
-      _contains(object) {
-        let rest = this._rest;
+      [_contains](object) {
+        let rest = this[_rest];
         if (rest === null)
           return false;
-        let bucket = this._getBucket(rest, object);
-        return this._findBucketIndex(bucket, object) >= 0;
+        let bucket = this[_getBucket](rest, object);
+        return this[_findBucketIndex](bucket, object) >= 0;
       }
       lookup(object) {
         if (dart.notNull(_isStringElement(object)) || dart.notNull(_isNumericElement(object))) {
           return dart.as(this.contains(object) ? object : null, E);
         }
-        return this._lookup(object);
+        return this[_lookup](object);
       }
-      _lookup(object) {
-        let rest = this._rest;
+      [_lookup](object) {
+        let rest = this[_rest];
         if (rest === null)
           return dart.as(null, E);
-        let bucket = this._getBucket(rest, object);
-        let index = this._findBucketIndex(bucket, object);
+        let bucket = this[_getBucket](rest, object);
+        let index = this[_findBucketIndex](bucket, object);
         if (index < 0)
           return dart.as(null, E);
         return dart.as(bucket.get(index), E);
       }
       add(element) {
         if (_isStringElement(element)) {
-          let strings = this._strings;
+          let strings = this[_strings];
           if (strings === null)
-            this._strings = strings = _newHashTable();
-          return this._addHashTableEntry(strings, element);
+            this[_strings] = strings = _newHashTable();
+          return this[_addHashTableEntry](strings, element);
         } else if (_isNumericElement(element)) {
-          let nums = this._nums;
+          let nums = this[_nums];
           if (nums === null)
-            this._nums = nums = _newHashTable();
-          return this._addHashTableEntry(nums, element);
+            this[_nums] = nums = _newHashTable();
+          return this[_addHashTableEntry](nums, element);
         } else {
-          return this._add(element);
+          return this[_add](element);
         }
       }
-      _add(element) {
-        let rest = this._rest;
+      [_add](element) {
+        let rest = this[_rest];
         if (rest === null)
-          this._rest = rest = _newHashTable();
-        let hash = this._computeHashCode(element);
+          this[_rest] = rest = _newHashTable();
+        let hash = this[_computeHashCode](element);
         let bucket = rest[hash];
         if (bucket === null) {
           _setTableEntry(rest, hash, [element]);
         } else {
-          let index = this._findBucketIndex(bucket, element);
+          let index = this[_findBucketIndex](bucket, element);
           if (index >= 0)
             return false;
           bucket.push(element);
         }
-        this._length++;
-        this._elements = null;
+        this[_length]++;
+        this[_elements] = null;
         return true;
       }
       addAll(objects) {
@@ -887,38 +934,38 @@ var collection;
       }
       remove(object) {
         if (_isStringElement(object)) {
-          return this._removeHashTableEntry(this._strings, object);
+          return this[_removeHashTableEntry](this[_strings], object);
         } else if (_isNumericElement(object)) {
-          return this._removeHashTableEntry(this._nums, object);
+          return this[_removeHashTableEntry](this[_nums], object);
         } else {
-          return this._remove(object);
+          return this[_remove](object);
         }
       }
-      _remove(object) {
-        let rest = this._rest;
+      [_remove](object) {
+        let rest = this[_rest];
         if (rest === null)
           return false;
-        let bucket = this._getBucket(rest, object);
-        let index = this._findBucketIndex(bucket, object);
+        let bucket = this[_getBucket](rest, object);
+        let index = this[_findBucketIndex](bucket, object);
         if (index < 0)
           return false;
-        this._length--;
-        this._elements = null;
+        this[_length]--;
+        this[_elements] = null;
         bucket.splice(index, 1);
         return true;
       }
       clear() {
-        if (this._length > 0) {
-          this._strings = this._nums = this._rest = this._elements = null;
-          this._length = 0;
+        if (this[_length] > 0) {
+          this[_strings] = this[_nums] = this[_rest] = this[_elements] = null;
+          this[_length] = 0;
         }
       }
-      _computeElements() {
-        if (this._elements !== null)
-          return this._elements;
-        let result = new core.List(this._length);
+      [_computeElements]() {
+        if (this[_elements] !== null)
+          return this[_elements];
+        let result = new core.List(this[_length]);
         let index = 0;
-        let strings = this._strings;
+        let strings = this[_strings];
         if (strings !== null) {
           let names = Object.getOwnPropertyNames(strings);
           let entries = names.length;
@@ -928,7 +975,7 @@ var collection;
             index++;
           }
         }
-        let nums = this._nums;
+        let nums = this[_nums];
         if (nums !== null) {
           let names = Object.getOwnPropertyNames(nums);
           let entries = names.length;
@@ -938,7 +985,7 @@ var collection;
             index++;
           }
         }
-        let rest = this._rest;
+        let rest = this[_rest];
         if (rest !== null) {
           let names = Object.getOwnPropertyNames(rest);
           let entries = names.length;
@@ -952,52 +999,52 @@ var collection;
             }
           }
         }
-        dart.assert(index === this._length);
-        return this._elements = result;
+        dart.assert(index === this[_length]);
+        return this[_elements] = result;
       }
-      _addHashTableEntry(table, element) {
+      [_addHashTableEntry](table, element) {
         if (_hasTableEntry(table, element))
           return false;
         _setTableEntry(table, element, 0);
-        this._length++;
-        this._elements = null;
+        this[_length]++;
+        this[_elements] = null;
         return true;
       }
-      _removeHashTableEntry(table, element) {
+      [_removeHashTableEntry](table, element) {
         if (dart.notNull(table !== null) && dart.notNull(_hasTableEntry(table, element))) {
           _deleteTableEntry(table, element);
-          this._length--;
-          this._elements = null;
+          this[_length]--;
+          this[_elements] = null;
           return true;
         } else {
           return false;
         }
       }
-      static _isStringElement(element) {
+      static [_isStringElement](element) {
         return dart.notNull(typeof element == string) && dart.notNull(!dart.equals(element, '__proto__'));
       }
-      static _isNumericElement(element) {
+      static [_isNumericElement](element) {
         return dart.notNull(dart.is(element, core.num)) && dart.notNull((element & 0x3ffffff) === element);
       }
-      _computeHashCode(element) {
+      [_computeHashCode](element) {
         return dart.dload(element, 'hashCode') & 0x3ffffff;
       }
-      static _hasTableEntry(table, key) {
+      static [_hasTableEntry](table, key) {
         let entry = table[key];
         return entry !== null;
       }
-      static _setTableEntry(table, key, value) {
+      static [_setTableEntry](table, key, value) {
         dart.assert(value !== null);
         table[key] = value;
       }
-      static _deleteTableEntry(table, key) {
+      static [_deleteTableEntry](table, key) {
         delete table[key];
       }
-      _getBucket(table, element) {
-        let hash = this._computeHashCode(element);
+      [_getBucket](table, element) {
+        let hash = this[_computeHashCode](element);
         return dart.as(table[hash], core.List);
       }
-      _findBucketIndex(bucket, element) {
+      [_findBucketIndex](bucket, element) {
         if (bucket === null)
           return -1;
         let length = bucket.length;
@@ -1007,7 +1054,7 @@ var collection;
         }
         return -1;
       }
-      static _newHashTable() {
+      static [_newHashTable]() {
         let table = Object.create(null);
         let temporaryKey = '<non-identifier-key>';
         _setTableEntry(table, temporaryKey, table);
@@ -1020,13 +1067,13 @@ var collection;
   let _HashSet = _HashSet$(dynamic);
   let _IdentityHashSet$ = dart.generic(function(E) {
     class _IdentityHashSet extends _HashSet$(E) {
-      _newSet() {
+      [_newSet]() {
         return new _IdentityHashSet();
       }
-      _computeHashCode(key) {
+      [_computeHashCode](key) {
         return core.identityHashCode(key) & 0x3ffffff;
       }
-      _findBucketIndex(bucket, element) {
+      [_findBucketIndex](bucket, element) {
         if (bucket === null)
           return -1;
         let length = bucket.length;
@@ -1040,45 +1087,47 @@ var collection;
     return _IdentityHashSet;
   });
   let _IdentityHashSet = _IdentityHashSet$(dynamic);
+  let _equality = Symbol('_equality');
+  let _hasher = Symbol('_hasher');
   let _CustomHashSet$ = dart.generic(function(E) {
     class _CustomHashSet extends _HashSet$(E) {
-      _CustomHashSet(_equality, _hasher, validKey) {
-        this._equality = _equality;
-        this._hasher = _hasher;
-        this._validKey = dart.as(validKey !== null ? validKey : (x) => dart.is(x, E), _Predicate);
+      _CustomHashSet($_equality, $_hasher, validKey) {
+        this[_equality] = $_equality;
+        this[_hasher] = $_hasher;
+        this[_validKey] = dart.as(validKey !== null ? validKey : (x) => dart.is(x, E), _Predicate);
         super._HashSet();
       }
-      _newSet() {
-        return new _CustomHashSet(this._equality, this._hasher, this._validKey);
+      [_newSet]() {
+        return new _CustomHashSet(this[_equality], this[_hasher], this[_validKey]);
       }
-      _findBucketIndex(bucket, element) {
+      [_findBucketIndex](bucket, element) {
         if (bucket === null)
           return -1;
         let length = bucket.length;
         for (let i = 0; i < length; i++) {
-          if (this._equality(dart.as(bucket[i], E), dart.as(element, E)))
+          if (this[_equality](dart.as(bucket[i], E), dart.as(element, E)))
             return i;
         }
         return -1;
       }
-      _computeHashCode(element) {
-        return this._hasher(dart.as(element, E)) & 0x3ffffff;
+      [_computeHashCode](element) {
+        return this[_hasher](dart.as(element, E)) & 0x3ffffff;
       }
       add(object) {
         return super._add(object);
       }
       contains(object) {
-        if (!dart.notNull(this._validKey(object)))
+        if (!dart.notNull(this[_validKey](object)))
           return false;
         return super._contains(object);
       }
       lookup(object) {
-        if (!dart.notNull(this._validKey(object)))
+        if (!dart.notNull(this[_validKey](object)))
           return dart.as(null, E);
         return super._lookup(object);
       }
       remove(object) {
-        if (!dart.notNull(this._validKey(object)))
+        if (!dart.notNull(this[_validKey](object)))
           return false;
         return super._remove(object);
       }
@@ -1088,26 +1137,26 @@ var collection;
   let _CustomHashSet = _CustomHashSet$(dynamic);
   let HashSetIterator$ = dart.generic(function(E) {
     class HashSetIterator extends dart.Object {
-      HashSetIterator(_set, _elements) {
-        this._set = _set;
-        this._elements = _elements;
-        this._offset = 0;
-        this._current = dart.as(null, E);
+      HashSetIterator($_set, $_elements) {
+        this[_set] = $_set;
+        this[_elements] = $_elements;
+        this[_offset] = 0;
+        this[_current] = dart.as(null, E);
       }
       get current() {
-        return this._current;
+        return this[_current];
       }
       moveNext() {
-        let elements = this._elements;
-        let offset = this._offset;
-        if (elements !== dart.dload(this._set, '_elements')) {
-          throw new core.ConcurrentModificationError(this._set);
+        let elements = this[_elements];
+        let offset = this[_offset];
+        if (elements !== dart.dload(this[_set], '_elements')) {
+          throw new core.ConcurrentModificationError(this[_set]);
         } else if (offset >= elements.length) {
-          this._current = dart.as(null, E);
+          this[_current] = dart.as(null, E);
           return false;
         } else {
-          this._current = dart.as(elements[offset], E);
-          this._offset = offset + 1;
+          this[_current] = dart.as(elements[offset], E);
+          this[_offset] = offset + 1;
           return true;
         }
       }
@@ -1115,166 +1164,169 @@ var collection;
     return HashSetIterator;
   });
   let HashSetIterator = HashSetIterator$(dynamic);
+  let _unsupported = Symbol('_unsupported');
+  let _element = Symbol('_element');
+  let _filterWhere = Symbol('_filterWhere');
   let _LinkedHashSet$ = dart.generic(function(E) {
     class _LinkedHashSet extends _HashSetBase$(E) {
       _LinkedHashSet() {
-        this._length = 0;
-        this._strings = null;
-        this._nums = null;
-        this._rest = null;
-        this._first = null;
-        this._last = null;
-        this._modifications = 0;
+        this[_length] = 0;
+        this[_strings] = null;
+        this[_nums] = null;
+        this[_rest] = null;
+        this[_first] = null;
+        this[_last] = null;
+        this[_modifications] = 0;
         super._HashSetBase();
       }
-      _newSet() {
+      [_newSet]() {
         return new _LinkedHashSet();
       }
-      _unsupported(operation) {
+      [_unsupported](operation) {
         throw `LinkedHashSet: unsupported ${operation}`;
       }
       get iterator() {
-        return dart.as(new LinkedHashSetIterator(this, this._modifications), core.Iterator$(E));
+        return dart.as(new LinkedHashSetIterator(this, this[_modifications]), core.Iterator$(E));
       }
       get length() {
-        return this._length;
+        return this[_length];
       }
       get isEmpty() {
-        return this._length === 0;
+        return this[_length] === 0;
       }
       get isNotEmpty() {
         return !dart.notNull(this.isEmpty);
       }
       contains(object) {
         if (_isStringElement(object)) {
-          let strings = this._strings;
+          let strings = this[_strings];
           if (strings === null)
             return false;
           let cell = dart.as(_getTableEntry(strings, object), LinkedHashSetCell);
           return cell !== null;
         } else if (_isNumericElement(object)) {
-          let nums = this._nums;
+          let nums = this[_nums];
           if (nums === null)
             return false;
           let cell = dart.as(_getTableEntry(nums, object), LinkedHashSetCell);
           return cell !== null;
         } else {
-          return this._contains(object);
+          return this[_contains](object);
         }
       }
-      _contains(object) {
-        let rest = this._rest;
+      [_contains](object) {
+        let rest = this[_rest];
         if (rest === null)
           return false;
-        let bucket = this._getBucket(rest, object);
-        return this._findBucketIndex(bucket, object) >= 0;
+        let bucket = this[_getBucket](rest, object);
+        return this[_findBucketIndex](bucket, object) >= 0;
       }
       lookup(object) {
         if (dart.notNull(_isStringElement(object)) || dart.notNull(_isNumericElement(object))) {
           return dart.as(this.contains(object) ? object : null, E);
         } else {
-          return this._lookup(object);
+          return this[_lookup](object);
         }
       }
-      _lookup(object) {
-        let rest = this._rest;
+      [_lookup](object) {
+        let rest = this[_rest];
         if (rest === null)
           return dart.as(null, E);
-        let bucket = this._getBucket(rest, object);
-        let index = this._findBucketIndex(bucket, object);
+        let bucket = this[_getBucket](rest, object);
+        let index = this[_findBucketIndex](bucket, object);
         if (index < 0)
           return dart.as(null, E);
         return dart.as(dart.dload(bucket.get(index), '_element'), E);
       }
       forEach(action) {
-        let cell = this._first;
-        let modifications = this._modifications;
+        let cell = this[_first];
+        let modifications = this[_modifications];
         while (cell !== null) {
-          action(dart.as(cell._element, E));
-          if (modifications !== this._modifications) {
+          action(dart.as(cell[_element], E));
+          if (modifications !== this[_modifications]) {
             throw new core.ConcurrentModificationError(this);
           }
-          cell = cell._next;
+          cell = cell[_next];
         }
       }
       get first() {
-        if (this._first === null)
+        if (this[_first] === null)
           throw new core.StateError("No elements");
-        return dart.as(this._first._element, E);
+        return dart.as(this[_first][_element], E);
       }
       get last() {
-        if (this._last === null)
+        if (this[_last] === null)
           throw new core.StateError("No elements");
-        return dart.as(this._last._element, E);
+        return dart.as(this[_last][_element], E);
       }
       add(element) {
         if (_isStringElement(element)) {
-          let strings = this._strings;
+          let strings = this[_strings];
           if (strings === null)
-            this._strings = strings = _newHashTable();
-          return this._addHashTableEntry(strings, element);
+            this[_strings] = strings = _newHashTable();
+          return this[_addHashTableEntry](strings, element);
         } else if (_isNumericElement(element)) {
-          let nums = this._nums;
+          let nums = this[_nums];
           if (nums === null)
-            this._nums = nums = _newHashTable();
-          return this._addHashTableEntry(nums, element);
+            this[_nums] = nums = _newHashTable();
+          return this[_addHashTableEntry](nums, element);
         } else {
-          return this._add(element);
+          return this[_add](element);
         }
       }
-      _add(element) {
-        let rest = this._rest;
+      [_add](element) {
+        let rest = this[_rest];
         if (rest === null)
-          this._rest = rest = _newHashTable();
-        let hash = this._computeHashCode(element);
+          this[_rest] = rest = _newHashTable();
+        let hash = this[_computeHashCode](element);
         let bucket = rest[hash];
         if (bucket === null) {
-          let cell = this._newLinkedCell(element);
+          let cell = this[_newLinkedCell](element);
           _setTableEntry(rest, hash, [cell]);
         } else {
-          let index = this._findBucketIndex(bucket, element);
+          let index = this[_findBucketIndex](bucket, element);
           if (index >= 0)
             return false;
-          let cell = this._newLinkedCell(element);
+          let cell = this[_newLinkedCell](element);
           bucket.push(cell);
         }
         return true;
       }
       remove(object) {
         if (_isStringElement(object)) {
-          return this._removeHashTableEntry(this._strings, object);
+          return this[_removeHashTableEntry](this[_strings], object);
         } else if (_isNumericElement(object)) {
-          return this._removeHashTableEntry(this._nums, object);
+          return this[_removeHashTableEntry](this[_nums], object);
         } else {
-          return this._remove(object);
+          return this[_remove](object);
         }
       }
-      _remove(object) {
-        let rest = this._rest;
+      [_remove](object) {
+        let rest = this[_rest];
         if (rest === null)
           return false;
-        let bucket = this._getBucket(rest, object);
-        let index = this._findBucketIndex(bucket, object);
+        let bucket = this[_getBucket](rest, object);
+        let index = this[_findBucketIndex](bucket, object);
         if (index < 0)
           return false;
         let cell = dart.as(bucket.splice(index, 1)[0], LinkedHashSetCell);
-        this._unlinkCell(cell);
+        this[_unlinkCell](cell);
         return true;
       }
       removeWhere(test) {
-        this._filterWhere(test, true);
+        this[_filterWhere](test, true);
       }
       retainWhere(test) {
-        this._filterWhere(test, false);
+        this[_filterWhere](test, false);
       }
-      _filterWhere(test, removeMatching) {
-        let cell = this._first;
+      [_filterWhere](test, removeMatching) {
+        let cell = this[_first];
         while (cell !== null) {
-          let element = dart.as(cell._element, E);
-          let next = cell._next;
-          let modifications = this._modifications;
+          let element = dart.as(cell[_element], E);
+          let next = cell[_next];
+          let modifications = this[_modifications];
           let shouldRemove = removeMatching === test(element);
-          if (modifications !== this._modifications) {
+          if (modifications !== this[_modifications]) {
             throw new core.ConcurrentModificationError(this);
           }
           if (shouldRemove)
@@ -1283,98 +1335,98 @@ var collection;
         }
       }
       clear() {
-        if (this._length > 0) {
-          this._strings = this._nums = this._rest = this._first = this._last = null;
-          this._length = 0;
-          this._modified();
+        if (this[_length] > 0) {
+          this[_strings] = this[_nums] = this[_rest] = this[_first] = this[_last] = null;
+          this[_length] = 0;
+          this[_modified]();
         }
       }
-      _addHashTableEntry(table, element) {
+      [_addHashTableEntry](table, element) {
         let cell = dart.as(_getTableEntry(table, element), LinkedHashSetCell);
         if (cell !== null)
           return false;
-        _setTableEntry(table, element, this._newLinkedCell(element));
+        _setTableEntry(table, element, this[_newLinkedCell](element));
         return true;
       }
-      _removeHashTableEntry(table, element) {
+      [_removeHashTableEntry](table, element) {
         if (table === null)
           return false;
         let cell = dart.as(_getTableEntry(table, element), LinkedHashSetCell);
         if (cell === null)
           return false;
-        this._unlinkCell(cell);
+        this[_unlinkCell](cell);
         _deleteTableEntry(table, element);
         return true;
       }
-      _modified() {
-        this._modifications = this._modifications + 1 & 67108863;
+      [_modified]() {
+        this[_modifications] = this[_modifications] + 1 & 67108863;
       }
-      _newLinkedCell(element) {
+      [_newLinkedCell](element) {
         let cell = new LinkedHashSetCell(element);
-        if (this._first === null) {
-          this._first = this._last = cell;
+        if (this[_first] === null) {
+          this[_first] = this[_last] = cell;
         } else {
-          let last = this._last;
-          cell._previous = last;
-          this._last = last._next = cell;
+          let last = this[_last];
+          cell[_previous] = last;
+          this[_last] = last[_next] = cell;
         }
-        this._length++;
-        this._modified();
+        this[_length]++;
+        this[_modified]();
         return cell;
       }
-      _unlinkCell(cell) {
-        let previous = cell._previous;
-        let next = cell._next;
+      [_unlinkCell](cell) {
+        let previous = cell[_previous];
+        let next = cell[_next];
         if (previous === null) {
-          dart.assert(dart.equals(cell, this._first));
-          this._first = next;
+          dart.assert(dart.equals(cell, this[_first]));
+          this[_first] = next;
         } else {
-          previous._next = next;
+          previous[_next] = next;
         }
         if (next === null) {
-          dart.assert(dart.equals(cell, this._last));
-          this._last = previous;
+          dart.assert(dart.equals(cell, this[_last]));
+          this[_last] = previous;
         } else {
-          next._previous = previous;
+          next[_previous] = previous;
         }
-        this._length--;
-        this._modified();
+        this[_length]--;
+        this[_modified]();
       }
-      static _isStringElement(element) {
+      static [_isStringElement](element) {
         return dart.notNull(typeof element == string) && dart.notNull(!dart.equals(element, '__proto__'));
       }
-      static _isNumericElement(element) {
+      static [_isNumericElement](element) {
         return dart.notNull(dart.is(element, core.num)) && dart.notNull((element & 0x3ffffff) === element);
       }
-      _computeHashCode(element) {
+      [_computeHashCode](element) {
         return dart.dload(element, 'hashCode') & 0x3ffffff;
       }
-      static _getTableEntry(table, key) {
+      static [_getTableEntry](table, key) {
         return table[key];
       }
-      static _setTableEntry(table, key, value) {
+      static [_setTableEntry](table, key, value) {
         dart.assert(value !== null);
         table[key] = value;
       }
-      static _deleteTableEntry(table, key) {
+      static [_deleteTableEntry](table, key) {
         delete table[key];
       }
-      _getBucket(table, element) {
-        let hash = this._computeHashCode(element);
+      [_getBucket](table, element) {
+        let hash = this[_computeHashCode](element);
         return dart.as(table[hash], core.List);
       }
-      _findBucketIndex(bucket, element) {
+      [_findBucketIndex](bucket, element) {
         if (bucket === null)
           return -1;
         let length = bucket.length;
         for (let i = 0; i < length; i++) {
           let cell = dart.as(bucket[i], LinkedHashSetCell);
-          if (dart.equals(cell._element, element))
+          if (dart.equals(cell[_element], element))
             return i;
         }
         return -1;
       }
-      static _newHashTable() {
+      static [_newHashTable]() {
         let table = Object.create(null);
         let temporaryKey = '<non-identifier-key>';
         _setTableEntry(table, temporaryKey, table);
@@ -1387,19 +1439,19 @@ var collection;
   let _LinkedHashSet = _LinkedHashSet$(dynamic);
   let _LinkedIdentityHashSet$ = dart.generic(function(E) {
     class _LinkedIdentityHashSet extends _LinkedHashSet$(E) {
-      _newSet() {
+      [_newSet]() {
         return new _LinkedIdentityHashSet();
       }
-      _computeHashCode(key) {
+      [_computeHashCode](key) {
         return core.identityHashCode(key) & 0x3ffffff;
       }
-      _findBucketIndex(bucket, element) {
+      [_findBucketIndex](bucket, element) {
         if (bucket === null)
           return -1;
         let length = bucket.length;
         for (let i = 0; i < length; i++) {
           let cell = dart.as(bucket[i], LinkedHashSetCell);
-          if (core.identical(cell._element, element))
+          if (core.identical(cell[_element], element))
             return i;
         }
         return -1;
@@ -1410,57 +1462,57 @@ var collection;
   let _LinkedIdentityHashSet = _LinkedIdentityHashSet$(dynamic);
   let _LinkedCustomHashSet$ = dart.generic(function(E) {
     class _LinkedCustomHashSet extends _LinkedHashSet$(E) {
-      _LinkedCustomHashSet(_equality, _hasher, validKey) {
-        this._equality = _equality;
-        this._hasher = _hasher;
-        this._validKey = dart.as(validKey !== null ? validKey : (x) => dart.is(x, E), _Predicate);
+      _LinkedCustomHashSet($_equality, $_hasher, validKey) {
+        this[_equality] = $_equality;
+        this[_hasher] = $_hasher;
+        this[_validKey] = dart.as(validKey !== null ? validKey : (x) => dart.is(x, E), _Predicate);
         super._LinkedHashSet();
       }
-      _newSet() {
-        return new _LinkedCustomHashSet(this._equality, this._hasher, this._validKey);
+      [_newSet]() {
+        return new _LinkedCustomHashSet(this[_equality], this[_hasher], this[_validKey]);
       }
-      _findBucketIndex(bucket, element) {
+      [_findBucketIndex](bucket, element) {
         if (bucket === null)
           return -1;
         let length = bucket.length;
         for (let i = 0; i < length; i++) {
           let cell = dart.as(bucket[i], LinkedHashSetCell);
-          if (this._equality(dart.as(cell._element, E), dart.as(element, E)))
+          if (this[_equality](dart.as(cell[_element], E), dart.as(element, E)))
             return i;
         }
         return -1;
       }
-      _computeHashCode(element) {
-        return this._hasher(dart.as(element, E)) & 0x3ffffff;
+      [_computeHashCode](element) {
+        return this[_hasher](dart.as(element, E)) & 0x3ffffff;
       }
       add(element) {
         return super._add(element);
       }
       contains(object) {
-        if (!dart.notNull(this._validKey(object)))
+        if (!dart.notNull(this[_validKey](object)))
           return false;
         return super._contains(object);
       }
       lookup(object) {
-        if (!dart.notNull(this._validKey(object)))
+        if (!dart.notNull(this[_validKey](object)))
           return dart.as(null, E);
         return super._lookup(object);
       }
       remove(object) {
-        if (!dart.notNull(this._validKey(object)))
+        if (!dart.notNull(this[_validKey](object)))
           return false;
         return super._remove(object);
       }
       containsAll(elements) {
         for (let element of elements) {
-          if (dart.notNull(!dart.notNull(this._validKey(element))) || dart.notNull(!dart.notNull(this.contains(element))))
+          if (dart.notNull(!dart.notNull(this[_validKey](element))) || dart.notNull(!dart.notNull(this.contains(element))))
             return false;
         }
         return true;
       }
       removeAll(elements) {
         for (let element of elements) {
-          if (this._validKey(element)) {
+          if (this[_validKey](element)) {
             super._remove(element);
           }
         }
@@ -1470,33 +1522,33 @@ var collection;
   });
   let _LinkedCustomHashSet = _LinkedCustomHashSet$(dynamic);
   class LinkedHashSetCell extends dart.Object {
-    LinkedHashSetCell(_element) {
-      this._element = _element;
-      this._next = null;
-      this._previous = null;
+    LinkedHashSetCell($_element) {
+      this[_element] = $_element;
+      this[_next] = null;
+      this[_previous] = null;
     }
   }
   let LinkedHashSetIterator$ = dart.generic(function(E) {
     class LinkedHashSetIterator extends dart.Object {
-      LinkedHashSetIterator(_set, _modifications) {
-        this._set = _set;
-        this._modifications = _modifications;
-        this._cell = null;
-        this._current = dart.as(null, E);
-        this._cell = dart.as(dart.dload(this._set, '_first'), LinkedHashSetCell);
+      LinkedHashSetIterator($_set, $_modifications) {
+        this[_set] = $_set;
+        this[_modifications] = $_modifications;
+        this[_cell] = null;
+        this[_current] = dart.as(null, E);
+        this[_cell] = dart.as(dart.dload(this[_set], '_first'), LinkedHashSetCell);
       }
       get current() {
-        return this._current;
+        return this[_current];
       }
       moveNext() {
-        if (this._modifications !== dart.dload(this._set, '_modifications')) {
-          throw new core.ConcurrentModificationError(this._set);
-        } else if (this._cell === null) {
-          this._current = dart.as(null, E);
+        if (this[_modifications] !== dart.dload(this[_set], '_modifications')) {
+          throw new core.ConcurrentModificationError(this[_set]);
+        } else if (this[_cell] === null) {
+          this[_current] = dart.as(null, E);
           return false;
         } else {
-          this._current = dart.as(this._cell._element, E);
-          this._cell = this._cell._next;
+          this[_current] = dart.as(this[_cell][_element], E);
+          this[_cell] = this[_cell][_next];
           return true;
         }
       }
@@ -1504,17 +1556,18 @@ var collection;
     return LinkedHashSetIterator;
   });
   let LinkedHashSetIterator = LinkedHashSetIterator$(dynamic);
+  let _source = Symbol('_source');
   let UnmodifiableListView$ = dart.generic(function(E) {
     class UnmodifiableListView extends _internal.UnmodifiableListBase$(E) {
       UnmodifiableListView(source) {
-        this._source = source;
+        this[_source] = source;
         super.UnmodifiableListBase();
       }
       get length() {
-        return this._source.length;
+        return this[_source].length;
       }
       get(index) {
-        return this._source.elementAt(index);
+        return this[_source].elementAt(index);
       }
     }
     return UnmodifiableListView;
@@ -1591,7 +1644,7 @@ var collection;
   let _HashSetBase$ = dart.generic(function(E) {
     class _HashSetBase extends SetBase$(E) {
       difference(other) {
-        let result = this._newSet();
+        let result = this[_newSet]();
         for (let element of this) {
           if (!dart.notNull(other.contains(element)))
             result.add(dart.as(element, E));
@@ -1599,7 +1652,7 @@ var collection;
         return result;
       }
       intersection(other) {
-        let result = this._newSet();
+        let result = this[_newSet]();
         for (let element of this) {
           if (other.contains(element))
             result.add(dart.as(element, E));
@@ -1610,7 +1663,7 @@ var collection;
         return ((_) => {
           _.addAll(this);
           return _;
-        }).bind(this)(this._newSet());
+        }).bind(this)(this[_newSet]());
       }
     }
     return _HashSetBase;
@@ -1856,6 +1909,8 @@ var collection;
     return IterableMixin;
   });
   let IterableMixin = IterableMixin$(dynamic);
+  let _isToStringVisiting = Symbol('_isToStringVisiting');
+  let _iterablePartsToStrings = Symbol('_iterablePartsToStrings');
   let IterableBase$ = dart.generic(function(E) {
     class IterableBase extends dart.Object {
       IterableBase() {
@@ -2093,14 +2148,14 @@ var collection;
         buffer.write(rightDelimiter);
         return buffer.toString();
       }
-      static _isToStringVisiting(o) {
+      static [_isToStringVisiting](o) {
         for (let i = 0; i < _toStringVisiting.length; i++) {
           if (core.identical(o, _toStringVisiting.get(i)))
             return true;
         }
         return false;
       }
-      static _iterablePartsToStrings(iterable, parts) {
+      static [_iterablePartsToStrings](iterable, parts) {
         let LENGTH_LIMIT = 80;
         let HEAD_COUNT = 3;
         let TAIL_COUNT = 2;
@@ -2187,30 +2242,33 @@ var collection;
     return IterableBase;
   });
   let IterableBase = IterableBase$(dynamic);
+  let _iterator = Symbol('_iterator');
+  let _state = Symbol('_state');
+  let _move = Symbol('_move');
   let HasNextIterator$ = dart.generic(function(E) {
     class HasNextIterator extends dart.Object {
-      HasNextIterator(_iterator) {
-        this._iterator = _iterator;
-        this._state = _NOT_MOVED_YET;
+      HasNextIterator($_iterator) {
+        this[_iterator] = $_iterator;
+        this[_state] = _NOT_MOVED_YET;
       }
       get hasNext() {
-        if (this._state === _NOT_MOVED_YET)
-          this._move();
-        return this._state === _HAS_NEXT_AND_NEXT_IN_CURRENT;
+        if (this[_state] === _NOT_MOVED_YET)
+          this[_move]();
+        return this[_state] === _HAS_NEXT_AND_NEXT_IN_CURRENT;
       }
       next() {
         if (!dart.notNull(this.hasNext))
           throw new core.StateError("No more elements");
-        dart.assert(this._state === _HAS_NEXT_AND_NEXT_IN_CURRENT);
-        let result = dart.as(this._iterator.current, E);
-        this._move();
+        dart.assert(this[_state] === _HAS_NEXT_AND_NEXT_IN_CURRENT);
+        let result = dart.as(this[_iterator].current, E);
+        this[_move]();
         return result;
       }
-      _move() {
-        if (this._iterator.moveNext()) {
-          this._state = _HAS_NEXT_AND_NEXT_IN_CURRENT;
+      [_move]() {
+        if (this[_iterator].moveNext()) {
+          this[_state] = _HAS_NEXT_AND_NEXT_IN_CURRENT;
         } else {
-          this._state = _NO_NEXT;
+          this[_state] = _NO_NEXT;
         }
       }
     }
@@ -2334,103 +2392,107 @@ var collection;
     return LinkedHashSet;
   });
   let LinkedHashSet = LinkedHashSet$(dynamic);
+  let _modificationCount = Symbol('_modificationCount');
+  let _insertAfter = Symbol('_insertAfter');
+  let _list = Symbol('_list');
+  let _unlink = Symbol('_unlink');
   let LinkedList$ = dart.generic(function(E) {
     class LinkedList extends IterableBase$(E) {
       LinkedList() {
-        this._modificationCount = 0;
-        this._length = 0;
-        this._next = null;
-        this._previous = null;
+        this[_modificationCount] = 0;
+        this[_length] = 0;
+        this[_next] = null;
+        this[_previous] = null;
         super.IterableBase();
-        this._next = this._previous = this;
+        this[_next] = this[_previous] = this;
       }
       addFirst(entry) {
-        this._insertAfter(this, entry);
+        this[_insertAfter](this, entry);
       }
       add(entry) {
-        this._insertAfter(this._previous, entry);
+        this[_insertAfter](this[_previous], entry);
       }
       addAll(entries) {
-        entries.forEach(((entry) => this._insertAfter(this._previous, dart.as(entry, E))).bind(this));
+        entries.forEach(((entry) => this[_insertAfter](this[_previous], dart.as(entry, E))).bind(this));
       }
       remove(entry) {
-        if (!dart.equals(entry._list, this))
+        if (!dart.equals(entry[_list], this))
           return false;
-        this._unlink(entry);
+        this[_unlink](entry);
         return true;
       }
       get iterator() {
         return new _LinkedListIterator(this);
       }
       get length() {
-        return this._length;
+        return this[_length];
       }
       clear() {
-        this._modificationCount++;
-        let next = this._next;
+        this[_modificationCount]++;
+        let next = this[_next];
         while (!dart.notNull(core.identical(next, this))) {
           let entry = dart.as(next, E);
-          next = entry._next;
-          entry._next = entry._previous = entry._list = null;
+          next = entry[_next];
+          entry[_next] = entry[_previous] = entry[_list] = null;
         }
-        this._next = this._previous = this;
-        this._length = 0;
+        this[_next] = this[_previous] = this;
+        this[_length] = 0;
       }
       get first() {
-        if (core.identical(this._next, this)) {
+        if (core.identical(this[_next], this)) {
           throw new core.StateError('No such element');
         }
-        return dart.as(this._next, E);
+        return dart.as(this[_next], E);
       }
       get last() {
-        if (core.identical(this._previous, this)) {
+        if (core.identical(this[_previous], this)) {
           throw new core.StateError('No such element');
         }
-        return dart.as(this._previous, E);
+        return dart.as(this[_previous], E);
       }
       get single() {
-        if (core.identical(this._previous, this)) {
+        if (core.identical(this[_previous], this)) {
           throw new core.StateError('No such element');
         }
-        if (!dart.notNull(core.identical(this._previous, this._next))) {
+        if (!dart.notNull(core.identical(this[_previous], this[_next]))) {
           throw new core.StateError('Too many elements');
         }
-        return dart.as(this._next, E);
+        return dart.as(this[_next], E);
       }
       forEach(action) {
-        let modificationCount = this._modificationCount;
-        let current = this._next;
+        let modificationCount = this[_modificationCount];
+        let current = this[_next];
         while (!dart.notNull(core.identical(current, this))) {
           action(dart.as(current, E));
-          if (modificationCount !== this._modificationCount) {
+          if (modificationCount !== this[_modificationCount]) {
             throw new core.ConcurrentModificationError(this);
           }
-          current = current._next;
+          current = current[_next];
         }
       }
       get isEmpty() {
-        return this._length === 0;
+        return this[_length] === 0;
       }
-      _insertAfter(entry, newEntry) {
+      [_insertAfter](entry, newEntry) {
         if (newEntry.list !== null) {
           throw new core.StateError('LinkedListEntry is already in a LinkedList');
         }
-        this._modificationCount++;
-        newEntry._list = this;
+        this[_modificationCount]++;
+        newEntry[_list] = this;
         let predecessor = entry;
-        let successor = entry._next;
-        successor._previous = newEntry;
-        newEntry._previous = predecessor;
-        newEntry._next = successor;
-        predecessor._next = newEntry;
-        this._length++;
-      }
-      _unlink(entry) {
-        this._modificationCount++;
-        entry._next._previous = entry._previous;
-        entry._previous._next = entry._next;
-        this._length--;
-        entry._list = entry._next = entry._previous = null;
+        let successor = entry[_next];
+        successor[_previous] = newEntry;
+        newEntry[_previous] = predecessor;
+        newEntry[_next] = successor;
+        predecessor[_next] = newEntry;
+        this[_length]++;
+      }
+      [_unlink](entry) {
+        this[_modificationCount]++;
+        entry[_next][_previous] = entry[_previous];
+        entry[_previous][_next] = entry[_next];
+        this[_length]--;
+        entry[_list] = entry[_next] = entry[_previous] = null;
       }
     }
     return LinkedList;
@@ -2439,24 +2501,24 @@ var collection;
   let _LinkedListIterator$ = dart.generic(function(E) {
     class _LinkedListIterator extends dart.Object {
       _LinkedListIterator(list) {
-        this._list = list;
-        this._modificationCount = list._modificationCount;
-        this._next = list._next;
-        this._current = null;
+        this[_list] = list;
+        this[_modificationCount] = list[_modificationCount];
+        this[_next] = list[_next];
+        this[_current] = null;
       }
       get current() {
-        return this._current;
+        return this[_current];
       }
       moveNext() {
-        if (core.identical(this._next, this._list)) {
-          this._current = null;
+        if (core.identical(this[_next], this[_list])) {
+          this[_current] = null;
           return false;
         }
-        if (this._modificationCount !== this._list._modificationCount) {
+        if (this[_modificationCount] !== this[_list][_modificationCount]) {
           throw new core.ConcurrentModificationError(this);
         }
-        this._current = dart.as(this._next, E);
-        this._next = this._next._next;
+        this[_current] = dart.as(this[_next], E);
+        this[_next] = this[_next][_next];
         return true;
       }
     }
@@ -2465,39 +2527,39 @@ var collection;
   let _LinkedListIterator = _LinkedListIterator$(dynamic);
   class _LinkedListLink extends dart.Object {
     _LinkedListLink() {
-      this._next = null;
-      this._previous = null;
+      this[_next] = null;
+      this[_previous] = null;
     }
   }
   let LinkedListEntry$ = dart.generic(function(E) {
     class LinkedListEntry extends dart.Object {
       LinkedListEntry() {
-        this._list = null;
-        this._next = null;
-        this._previous = null;
+        this[_list] = null;
+        this[_next] = null;
+        this[_previous] = null;
       }
       get list() {
-        return this._list;
+        return this[_list];
       }
       unlink() {
-        this._list._unlink(this);
+        this[_list]._unlink(this);
       }
       get next() {
-        if (core.identical(this._next, this._list))
+        if (core.identical(this[_next], this[_list]))
           return null;
-        let result = dart.as(this._next, E);
+        let result = dart.as(this[_next], E);
         return result;
       }
       get previous() {
-        if (core.identical(this._previous, this._list))
+        if (core.identical(this[_previous], this[_list]))
           return null;
-        return dart.as(this._previous, E);
+        return dart.as(this[_previous], E);
       }
       insertAfter(entry) {
-        this._list._insertAfter(this, entry);
+        this[_list]._insertAfter(this, entry);
       }
       insertBefore(entry) {
-        this._list._insertAfter(this._previous, entry);
+        this[_list]._insertAfter(this[_previous], entry);
       }
     }
     return LinkedListEntry;
@@ -2512,6 +2574,7 @@ var collection;
     return ListBase;
   });
   let ListBase = ListBase$(dynamic);
+  let _filter = Symbol('_filter');
   let ListMixin$ = dart.generic(function(E) {
     class ListMixin extends dart.Object {
       get iterator() {
@@ -2737,7 +2800,7 @@ var collection;
       retainWhere(test) {
         _filter(this, dart.as(test, dart.throw_("Unimplemented type (dynamic) → bool")), true);
       }
-      static _filter(source, test, retainMatching) {
+      static [_filter](source, test, retainMatching) {
         let retained = new List.from([]);
         let length = source.length;
         for (let i = 0; i < length; i++) {
@@ -3023,30 +3086,30 @@ var collection;
   let UnmodifiableMapBase = UnmodifiableMapBase$(dynamic, dynamic);
   let _MapBaseValueIterable$ = dart.generic(function(V) {
     class _MapBaseValueIterable extends IterableBase$(V) {
-      _MapBaseValueIterable(_map) {
-        this._map = _map;
+      _MapBaseValueIterable($_map) {
+        this[_map] = $_map;
         super.IterableBase();
       }
       get length() {
-        return this._map.length;
+        return this[_map].length;
       }
       get isEmpty() {
-        return this._map.isEmpty;
+        return this[_map].isEmpty;
       }
       get isNotEmpty() {
-        return this._map.isNotEmpty;
+        return this[_map].isNotEmpty;
       }
       get first() {
-        return dart.as(this._map.get(this._map.keys.first), V);
+        return dart.as(this[_map].get(this[_map].keys.first), V);
       }
       get single() {
-        return dart.as(this._map.get(this._map.keys.single), V);
+        return dart.as(this[_map].get(this[_map].keys.single), V);
       }
       get last() {
-        return dart.as(this._map.get(this._map.keys.last), V);
+        return dart.as(this[_map].get(this[_map].keys.last), V);
       }
       get iterator() {
-        return new _MapBaseValueIterator(this._map);
+        return new _MapBaseValueIterator(this[_map]);
       }
     }
     return _MapBaseValueIterable;
@@ -3055,20 +3118,20 @@ var collection;
   let _MapBaseValueIterator$ = dart.generic(function(V) {
     class _MapBaseValueIterator extends dart.Object {
       _MapBaseValueIterator(map) {
-        this._map = map;
-        this._keys = map.keys.iterator;
-        this._current = dart.as(null, V);
+        this[_map] = map;
+        this[_keys] = map.keys.iterator;
+        this[_current] = dart.as(null, V);
       }
       moveNext() {
-        if (this._keys.moveNext()) {
-          this._current = dart.as(this._map.get(this._keys.current), V);
+        if (this[_keys].moveNext()) {
+          this[_current] = dart.as(this[_map].get(this[_keys].current), V);
           return true;
         }
-        this._current = dart.as(null, V);
+        this[_current] = dart.as(null, V);
         return false;
       }
       get current() {
-        return this._current;
+        return this[_current];
       }
     }
     return _MapBaseValueIterator;
@@ -3098,52 +3161,52 @@ var collection;
   let MapView$ = dart.generic(function(K, V) {
     class MapView extends dart.Object {
       MapView(map) {
-        this._map = map;
+        this[_map] = map;
       }
       get(key) {
-        return this._map.get(key);
+        return this[_map].get(key);
       }
       set(key, value) {
-        this._map.set(key, value);
+        this[_map].set(key, value);
       }
       addAll(other) {
-        this._map.addAll(other);
+        this[_map].addAll(other);
       }
       clear() {
-        this._map.clear();
+        this[_map].clear();
       }
       putIfAbsent(key, ifAbsent) {
-        return this._map.putIfAbsent(key, ifAbsent);
+        return this[_map].putIfAbsent(key, ifAbsent);
       }
       containsKey(key) {
-        return this._map.containsKey(key);
+        return this[_map].containsKey(key);
       }
       containsValue(value) {
-        return this._map.containsValue(value);
+        return this[_map].containsValue(value);
       }
       forEach(action) {
-        this._map.forEach(action);
+        this[_map].forEach(action);
       }
       get isEmpty() {
-        return this._map.isEmpty;
+        return this[_map].isEmpty;
       }
       get isNotEmpty() {
-        return this._map.isNotEmpty;
+        return this[_map].isNotEmpty;
       }
       get length() {
-        return this._map.length;
+        return this[_map].length;
       }
       get keys() {
-        return this._map.keys;
+        return this[_map].keys;
       }
       remove(key) {
-        return this._map.remove(key);
+        return this[_map].remove(key);
       }
       toString() {
-        return this._map.toString();
+        return this[_map].toString();
       }
       get values() {
-        return this._map.values;
+        return this[_map].values;
       }
     }
     return MapView;
@@ -3155,6 +3218,10 @@ var collection;
     return UnmodifiableMapView;
   });
   let UnmodifiableMapView = UnmodifiableMapView$(dynamic, dynamic);
+  let _toStringVisiting = Symbol('_toStringVisiting');
+  let _id = Symbol('_id');
+  let _fillMapWithMappedIterable = Symbol('_fillMapWithMappedIterable');
+  let _fillMapWithIterables = Symbol('_fillMapWithIterables');
   class Maps extends dart.Object {
     static containsValue(map, value) {
       for (let v of map.values) {
@@ -3208,7 +3275,7 @@ var collection;
       }
       let result = new core.StringBuffer();
       try {
-        IterableBase._toStringVisiting.add(m);
+        IterableBase[_toStringVisiting].add(m);
         result.write('{');
         let first = true;
         m.forEach(((k, v) => {
@@ -3222,15 +3289,15 @@ var collection;
         }).bind(this));
         result.write('}');
       } finally {
-        dart.assert(core.identical(IterableBase._toStringVisiting.last, m));
-        IterableBase._toStringVisiting.removeLast();
+        dart.assert(core.identical(IterableBase[_toStringVisiting].last, m));
+        IterableBase[_toStringVisiting].removeLast();
       }
       return result.toString();
     }
-    static _id(x) {
+    static [_id](x) {
       return x;
     }
-    static _fillMapWithMappedIterable(map, iterable, key, value) {
+    static [_fillMapWithMappedIterable](map, iterable, key, value) {
       if (key === null)
         key = _id;
       if (value === null)
@@ -3239,7 +3306,7 @@ var collection;
         map.set(key(element), value(element));
       }
     }
-    static _fillMapWithIterables(map, keys, values) {
+    static [_fillMapWithIterables](map, keys, values) {
       let keyIterator = keys.iterator;
       let valueIterator = values.iterator;
       let hasNextKey = keyIterator.moveNext();
@@ -3267,46 +3334,48 @@ var collection;
     return Queue;
   });
   let Queue = Queue$(dynamic);
+  let _link = Symbol('_link');
+  let _asNonSentinelEntry = Symbol('_asNonSentinelEntry');
   let DoubleLinkedQueueEntry$ = dart.generic(function(E) {
     class DoubleLinkedQueueEntry extends dart.Object {
       DoubleLinkedQueueEntry(e) {
-        this._element = e;
-        this._previous = null;
-        this._next = null;
+        this[_element] = e;
+        this[_previous] = null;
+        this[_next] = null;
       }
-      _link(previous, next) {
-        this._next = next;
-        this._previous = previous;
-        previous._next = this;
-        next._previous = this;
+      [_link](previous, next) {
+        this[_next] = next;
+        this[_previous] = previous;
+        previous[_next] = this;
+        next[_previous] = this;
       }
       append(e) {
-        new DoubleLinkedQueueEntry(e)._link(this, this._next);
+        new DoubleLinkedQueueEntry(e)._link(this, this[_next]);
       }
       prepend(e) {
-        new DoubleLinkedQueueEntry(e)._link(this._previous, this);
+        new DoubleLinkedQueueEntry(e)._link(this[_previous], this);
       }
       remove() {
-        this._previous._next = this._next;
-        this._next._previous = this._previous;
-        this._next = null;
-        this._previous = null;
-        return this._element;
+        this[_previous][_next] = this[_next];
+        this[_next][_previous] = this[_previous];
+        this[_next] = null;
+        this[_previous] = null;
+        return this[_element];
       }
-      _asNonSentinelEntry() {
+      [_asNonSentinelEntry]() {
         return this;
       }
       previousEntry() {
-        return this._previous._asNonSentinelEntry();
+        return this[_previous]._asNonSentinelEntry();
       }
       nextEntry() {
-        return this._next._asNonSentinelEntry();
+        return this[_next]._asNonSentinelEntry();
       }
       get element() {
-        return this._element;
+        return this[_element];
       }
       set element(e) {
-        this._element = e;
+        this[_element] = e;
       }
     }
     return DoubleLinkedQueueEntry;
@@ -3316,12 +3385,12 @@ var collection;
     class _DoubleLinkedQueueEntrySentinel extends DoubleLinkedQueueEntry$(E) {
       _DoubleLinkedQueueEntrySentinel() {
         super.DoubleLinkedQueueEntry(dart.as(null, E));
-        this._link(this, this);
+        this[_link](this, this);
       }
       remove() {
         throw _internal.IterableElementError.noElement();
       }
-      _asNonSentinelEntry() {
+      [_asNonSentinelEntry]() {
         return null;
       }
       set element(e) {
@@ -3334,13 +3403,15 @@ var collection;
     return _DoubleLinkedQueueEntrySentinel;
   });
   let _DoubleLinkedQueueEntrySentinel = _DoubleLinkedQueueEntrySentinel$(dynamic);
+  let _sentinel = Symbol('_sentinel');
+  let _elementCount = Symbol('_elementCount');
   let DoubleLinkedQueue$ = dart.generic(function(E) {
     class DoubleLinkedQueue extends IterableBase$(E) {
       DoubleLinkedQueue() {
-        this._sentinel = null;
-        this._elementCount = 0;
+        this[_sentinel] = null;
+        this[_elementCount] = 0;
         super.IterableBase();
-        this._sentinel = new _DoubleLinkedQueueEntrySentinel();
+        this[_sentinel] = new _DoubleLinkedQueueEntrySentinel();
       }
       DoubleLinkedQueue$from(elements) {
         let list = dart.as(new DoubleLinkedQueue(), Queue$(E));
@@ -3350,101 +3421,101 @@ var collection;
         return dart.as(list, DoubleLinkedQueue$(E));
       }
       get length() {
-        return this._elementCount;
+        return this[_elementCount];
       }
       addLast(value) {
-        this._sentinel.prepend(value);
-        this._elementCount++;
+        this[_sentinel].prepend(value);
+        this[_elementCount]++;
       }
       addFirst(value) {
-        this._sentinel.append(value);
-        this._elementCount++;
+        this[_sentinel].append(value);
+        this[_elementCount]++;
       }
       add(value) {
-        this._sentinel.prepend(value);
-        this._elementCount++;
+        this[_sentinel].prepend(value);
+        this[_elementCount]++;
       }
       addAll(iterable) {
         for (let value of iterable) {
-          this._sentinel.prepend(value);
-          this._elementCount++;
+          this[_sentinel].prepend(value);
+          this[_elementCount]++;
         }
       }
       removeLast() {
-        let result = this._sentinel._previous.remove();
-        this._elementCount--;
+        let result = this[_sentinel][_previous].remove();
+        this[_elementCount]--;
         return result;
       }
       removeFirst() {
-        let result = this._sentinel._next.remove();
-        this._elementCount--;
+        let result = this[_sentinel][_next].remove();
+        this[_elementCount]--;
         return result;
       }
       remove(o) {
-        let entry = this._sentinel._next;
-        while (!dart.notNull(core.identical(entry, this._sentinel))) {
+        let entry = this[_sentinel][_next];
+        while (!dart.notNull(core.identical(entry, this[_sentinel]))) {
           if (dart.equals(entry.element, o)) {
             entry.remove();
-            this._elementCount--;
+            this[_elementCount]--;
             return true;
           }
-          entry = entry._next;
+          entry = entry[_next];
         }
         return false;
       }
-      _filter(test, removeMatching) {
-        let entry = this._sentinel._next;
-        while (!dart.notNull(core.identical(entry, this._sentinel))) {
-          let next = entry._next;
+      [_filter](test, removeMatching) {
+        let entry = this[_sentinel][_next];
+        while (!dart.notNull(core.identical(entry, this[_sentinel]))) {
+          let next = entry[_next];
           if (core.identical(removeMatching, test(entry.element))) {
             entry.remove();
-            this._elementCount--;
+            this[_elementCount]--;
           }
           entry = next;
         }
       }
       removeWhere(test) {
-        this._filter(test, true);
+        this[_filter](test, true);
       }
       retainWhere(test) {
-        this._filter(test, false);
+        this[_filter](test, false);
       }
       get first() {
-        return this._sentinel._next.element;
+        return this[_sentinel][_next].element;
       }
       get last() {
-        return this._sentinel._previous.element;
+        return this[_sentinel][_previous].element;
       }
       get single() {
-        if (core.identical(this._sentinel._next, this._sentinel._previous)) {
-          return this._sentinel._next.element;
+        if (core.identical(this[_sentinel][_next], this[_sentinel][_previous])) {
+          return this[_sentinel][_next].element;
         }
         throw _internal.IterableElementError.tooMany();
       }
       lastEntry() {
-        return this._sentinel.previousEntry();
+        return this[_sentinel].previousEntry();
       }
       firstEntry() {
-        return this._sentinel.nextEntry();
+        return this[_sentinel].nextEntry();
       }
       get isEmpty() {
-        return core.identical(this._sentinel._next, this._sentinel);
+        return core.identical(this[_sentinel][_next], this[_sentinel]);
       }
       clear() {
-        this._sentinel._next = this._sentinel;
-        this._sentinel._previous = this._sentinel;
-        this._elementCount = 0;
+        this[_sentinel][_next] = this[_sentinel];
+        this[_sentinel][_previous] = this[_sentinel];
+        this[_elementCount] = 0;
       }
       forEachEntry(f) {
-        let entry = this._sentinel._next;
-        while (!dart.notNull(core.identical(entry, this._sentinel))) {
-          let nextEntry = entry._next;
+        let entry = this[_sentinel][_next];
+        while (!dart.notNull(core.identical(entry, this[_sentinel]))) {
+          let nextEntry = entry[_next];
           f(entry);
           entry = nextEntry;
         }
       }
       get iterator() {
-        return new _DoubleLinkedQueueIterator(this._sentinel);
+        return new _DoubleLinkedQueueIterator(this[_sentinel]);
       }
       toString() {
         return IterableBase.iterableToFullString(this, '{', '}');
@@ -3454,39 +3525,49 @@ var collection;
     return DoubleLinkedQueue;
   });
   let DoubleLinkedQueue = DoubleLinkedQueue$(dynamic);
+  let _nextEntry = Symbol('_nextEntry');
   let _DoubleLinkedQueueIterator$ = dart.generic(function(E) {
     class _DoubleLinkedQueueIterator extends dart.Object {
       _DoubleLinkedQueueIterator(sentinel) {
-        this._sentinel = sentinel;
-        this._nextEntry = sentinel._next;
-        this._current = dart.as(null, E);
+        this[_sentinel] = sentinel;
+        this[_nextEntry] = sentinel[_next];
+        this[_current] = dart.as(null, E);
       }
       moveNext() {
-        if (!dart.notNull(core.identical(this._nextEntry, this._sentinel))) {
-          this._current = this._nextEntry._element;
-          this._nextEntry = this._nextEntry._next;
+        if (!dart.notNull(core.identical(this[_nextEntry], this[_sentinel]))) {
+          this[_current] = this[_nextEntry][_element];
+          this[_nextEntry] = this[_nextEntry][_next];
           return true;
         }
-        this._current = dart.as(null, E);
-        this._nextEntry = this._sentinel = null;
+        this[_current] = dart.as(null, E);
+        this[_nextEntry] = this[_sentinel] = null;
         return false;
       }
       get current() {
-        return this._current;
+        return this[_current];
       }
     }
     return _DoubleLinkedQueueIterator;
   });
   let _DoubleLinkedQueueIterator = _DoubleLinkedQueueIterator$(dynamic);
+  let _head = Symbol('_head');
+  let _tail = Symbol('_tail');
+  let _table = Symbol('_table');
+  let _checkModification = Symbol('_checkModification');
+  let _writeToList = Symbol('_writeToList');
+  let _preGrow = Symbol('_preGrow');
+  let _grow = Symbol('_grow');
+  let _isPowerOf2 = Symbol('_isPowerOf2');
+  let _nextPowerOf2 = Symbol('_nextPowerOf2');
   let ListQueue$ = dart.generic(function(E) {
     class ListQueue extends IterableBase$(E) {
       ListQueue(initialCapacity) {
         if (initialCapacity === void 0)
           initialCapacity = null;
-        this._head = 0;
-        this._tail = 0;
-        this._table = null;
-        this._modificationCount = 0;
+        this[_head] = 0;
+        this[_tail] = 0;
+        this[_table] = null;
+        this[_modificationCount] = 0;
         super.IterableBase();
         if (dart.notNull(initialCapacity === null) || dart.notNull(initialCapacity < _INITIAL_CAPACITY)) {
           initialCapacity = _INITIAL_CAPACITY;
@@ -3494,16 +3575,16 @@ var collection;
           initialCapacity = _nextPowerOf2(initialCapacity);
         }
         dart.assert(_isPowerOf2(initialCapacity));
-        this._table = new core.List(initialCapacity);
+        this[_table] = new core.List(initialCapacity);
       }
       ListQueue$from(elements) {
         if (dart.is(elements, core.List)) {
           let length = elements.length;
           let queue = dart.as(new ListQueue(length + 1), ListQueue$(E));
-          dart.assert(queue._table.length > length);
+          dart.assert(queue[_table].length > length);
           let sourceList = elements;
-          queue._table.setRange(0, length, dart.as(sourceList, core.Iterable$(E)), 0);
-          queue._tail = length;
+          queue[_table].setRange(0, length, dart.as(sourceList, core.Iterable$(E)), 0);
+          queue[_tail] = length;
           return queue;
         } else {
           let capacity = _INITIAL_CAPACITY;
@@ -3521,38 +3602,38 @@ var collection;
         return new _ListQueueIterator(this);
       }
       forEach(action) {
-        let modificationCount = this._modificationCount;
-        for (let i = this._head; i !== this._tail; i = i + 1 & this._table.length - 1) {
-          action(this._table.get(i));
-          this._checkModification(modificationCount);
+        let modificationCount = this[_modificationCount];
+        for (let i = this[_head]; i !== this[_tail]; i = i + 1 & this[_table].length - 1) {
+          action(this[_table].get(i));
+          this[_checkModification](modificationCount);
         }
       }
       get isEmpty() {
-        return this._head === this._tail;
+        return this[_head] === this[_tail];
       }
       get length() {
-        return this._tail - this._head & this._table.length - 1;
+        return this[_tail] - this[_head] & this[_table].length - 1;
       }
       get first() {
-        if (this._head === this._tail)
+        if (this[_head] === this[_tail])
           throw _internal.IterableElementError.noElement();
-        return this._table.get(this._head);
+        return this[_table].get(this[_head]);
       }
       get last() {
-        if (this._head === this._tail)
+        if (this[_head] === this[_tail])
           throw _internal.IterableElementError.noElement();
-        return this._table.get(this._tail - 1 & this._table.length - 1);
+        return this[_table].get(this[_tail] - 1 & this[_table].length - 1);
       }
       get single() {
-        if (this._head === this._tail)
+        if (this[_head] === this[_tail])
           throw _internal.IterableElementError.noElement();
         if (this.length > 1)
           throw _internal.IterableElementError.tooMany();
-        return this._table.get(this._head);
+        return this[_table].get(this[_head]);
       }
       elementAt(index) {
         core.RangeError.checkValidIndex(index, this);
-        return this._table.get(this._head + index & this._table.length - 1);
+        return this[_table].get(this[_head] + index & this[_table].length - 1);
       }
       toList(opt$) {
         let growable = opt$.growable === void 0 ? true : opt$.growable;
@@ -3565,116 +3646,116 @@ var collection;
         } else {
           list = new core.List(this.length);
         }
-        this._writeToList(list);
+        this[_writeToList](list);
         return list;
       }
       add(element) {
-        this._add(element);
+        this[_add](element);
       }
       addAll(elements) {
         if (dart.is(elements, core.List)) {
           let list = dart.as(elements, core.List);
           let addCount = list.length;
           let length = this.length;
-          if (length + addCount >= this._table.length) {
-            this._preGrow(length + addCount);
-            this._table.setRange(length, length + addCount, dart.as(list, core.Iterable$(E)), 0);
-            this._tail = addCount;
+          if (length + addCount >= this[_table].length) {
+            this[_preGrow](length + addCount);
+            this[_table].setRange(length, length + addCount, dart.as(list, core.Iterable$(E)), 0);
+            this[_tail] = addCount;
           } else {
-            let endSpace = this._table.length - this._tail;
+            let endSpace = this[_table].length - this[_tail];
             if (addCount < endSpace) {
-              this._table.setRange(this._tail, this._tail + addCount, dart.as(list, core.Iterable$(E)), 0);
-              this._tail = addCount;
+              this[_table].setRange(this[_tail], this[_tail] + addCount, dart.as(list, core.Iterable$(E)), 0);
+              this[_tail] = addCount;
             } else {
               let preSpace = addCount - endSpace;
-              this._table.setRange(this._tail, this._tail + endSpace, dart.as(list, core.Iterable$(E)), 0);
-              this._table.setRange(0, preSpace, dart.as(list, core.Iterable$(E)), endSpace);
-              this._tail = preSpace;
+              this[_table].setRange(this[_tail], this[_tail] + endSpace, dart.as(list, core.Iterable$(E)), 0);
+              this[_table].setRange(0, preSpace, dart.as(list, core.Iterable$(E)), endSpace);
+              this[_tail] = preSpace;
             }
           }
-          this._modificationCount++;
+          this[_modificationCount]++;
         } else {
           for (let element of elements)
-            this._add(element);
+            this[_add](element);
         }
       }
       remove(object) {
-        for (let i = this._head; i !== this._tail; i = i + 1 & this._table.length - 1) {
-          let element = this._table.get(i);
+        for (let i = this[_head]; i !== this[_tail]; i = i + 1 & this[_table].length - 1) {
+          let element = this[_table].get(i);
           if (dart.equals(element, object)) {
-            this._remove(i);
-            this._modificationCount++;
+            this[_remove](i);
+            this[_modificationCount]++;
             return true;
           }
         }
         return false;
       }
-      _filterWhere(test, removeMatching) {
-        let index = this._head;
-        let modificationCount = this._modificationCount;
-        let i = this._head;
-        while (i !== this._tail) {
-          let element = this._table.get(i);
+      [_filterWhere](test, removeMatching) {
+        let index = this[_head];
+        let modificationCount = this[_modificationCount];
+        let i = this[_head];
+        while (i !== this[_tail]) {
+          let element = this[_table].get(i);
           let remove = core.identical(removeMatching, test(element));
-          this._checkModification(modificationCount);
+          this[_checkModification](modificationCount);
           if (remove) {
-            i = this._remove(i);
-            modificationCount = ++this._modificationCount;
+            i = this[_remove](i);
+            modificationCount = ++this[_modificationCount];
           } else {
-            i = i + 1 & this._table.length - 1;
+            i = i + 1 & this[_table].length - 1;
           }
         }
       }
       removeWhere(test) {
-        this._filterWhere(test, true);
+        this[_filterWhere](test, true);
       }
       retainWhere(test) {
-        this._filterWhere(test, false);
+        this[_filterWhere](test, false);
       }
       clear() {
-        if (this._head !== this._tail) {
-          for (let i = this._head; i !== this._tail; i = i + 1 & this._table.length - 1) {
-            this._table.set(i, dart.as(null, E));
+        if (this[_head] !== this[_tail]) {
+          for (let i = this[_head]; i !== this[_tail]; i = i + 1 & this[_table].length - 1) {
+            this[_table].set(i, dart.as(null, E));
           }
-          this._head = this._tail = 0;
-          this._modificationCount++;
+          this[_head] = this[_tail] = 0;
+          this[_modificationCount]++;
         }
       }
       toString() {
         return IterableBase.iterableToFullString(this, "{", "}");
       }
       addLast(element) {
-        this._add(element);
+        this[_add](element);
       }
       addFirst(element) {
-        this._head = this._head - 1 & this._table.length - 1;
-        this._table.set(this._head, element);
-        if (this._head === this._tail)
-          this._grow();
-        this._modificationCount++;
+        this[_head] = this[_head] - 1 & this[_table].length - 1;
+        this[_table].set(this[_head], element);
+        if (this[_head] === this[_tail])
+          this[_grow]();
+        this[_modificationCount]++;
       }
       removeFirst() {
-        if (this._head === this._tail)
+        if (this[_head] === this[_tail])
           throw _internal.IterableElementError.noElement();
-        this._modificationCount++;
-        let result = this._table.get(this._head);
-        this._table.set(this._head, dart.as(null, E));
-        this._head = this._head + 1 & this._table.length - 1;
+        this[_modificationCount]++;
+        let result = this[_table].get(this[_head]);
+        this[_table].set(this[_head], dart.as(null, E));
+        this[_head] = this[_head] + 1 & this[_table].length - 1;
         return result;
       }
       removeLast() {
-        if (this._head === this._tail)
+        if (this[_head] === this[_tail])
           throw _internal.IterableElementError.noElement();
-        this._modificationCount++;
-        this._tail = this._tail - 1 & this._table.length - 1;
-        let result = this._table.get(this._tail);
-        this._table.set(this._tail, dart.as(null, E));
+        this[_modificationCount]++;
+        this[_tail] = this[_tail] - 1 & this[_table].length - 1;
+        let result = this[_table].get(this[_tail]);
+        this[_table].set(this[_tail], dart.as(null, E));
         return result;
       }
-      static _isPowerOf2(number) {
+      static [_isPowerOf2](number) {
         return (number & number - 1) === 0;
       }
-      static _nextPowerOf2(number) {
+      static [_nextPowerOf2](number) {
         dart.assert(number > 0);
         number = (number << 1) - 1;
         for (;;) {
@@ -3684,74 +3765,74 @@ var collection;
           number = nextNumber;
         }
       }
-      _checkModification(expectedModificationCount) {
-        if (expectedModificationCount !== this._modificationCount) {
+      [_checkModification](expectedModificationCount) {
+        if (expectedModificationCount !== this[_modificationCount]) {
           throw new core.ConcurrentModificationError(this);
         }
       }
-      _add(element) {
-        this._table.set(this._tail, element);
-        this._tail = this._tail + 1 & this._table.length - 1;
-        if (this._head === this._tail)
-          this._grow();
-        this._modificationCount++;
+      [_add](element) {
+        this[_table].set(this[_tail], element);
+        this[_tail] = this[_tail] + 1 & this[_table].length - 1;
+        if (this[_head] === this[_tail])
+          this[_grow]();
+        this[_modificationCount]++;
       }
-      _remove(offset) {
-        let mask = this._table.length - 1;
-        let startDistance = offset - this._head & mask;
-        let endDistance = this._tail - offset & mask;
+      [_remove](offset) {
+        let mask = this[_table].length - 1;
+        let startDistance = offset - this[_head] & mask;
+        let endDistance = this[_tail] - offset & mask;
         if (startDistance < endDistance) {
           let i = offset;
-          while (i !== this._head) {
+          while (i !== this[_head]) {
             let prevOffset = i - 1 & mask;
-            this._table.set(i, this._table.get(prevOffset));
+            this[_table].set(i, this[_table].get(prevOffset));
             i = prevOffset;
           }
-          this._table.set(this._head, dart.as(null, E));
-          this._head = this._head + 1 & mask;
+          this[_table].set(this[_head], dart.as(null, E));
+          this[_head] = this[_head] + 1 & mask;
           return offset + 1 & mask;
         } else {
-          this._tail = this._tail - 1 & mask;
+          this[_tail] = this[_tail] - 1 & mask;
           let i = offset;
-          while (i !== this._tail) {
+          while (i !== this[_tail]) {
             let nextOffset = i + 1 & mask;
-            this._table.set(i, this._table.get(nextOffset));
+            this[_table].set(i, this[_table].get(nextOffset));
             i = nextOffset;
           }
-          this._table.set(this._tail, dart.as(null, E));
+          this[_table].set(this[_tail], dart.as(null, E));
           return offset;
         }
       }
-      _grow() {
-        let newTable = new core.List(this._table.length * 2);
-        let split = this._table.length - this._head;
-        newTable.setRange(0, split, this._table, this._head);
-        newTable.setRange(split, split + this._head, this._table, 0);
-        this._head = 0;
-        this._tail = this._table.length;
-        this._table = newTable;
+      [_grow]() {
+        let newTable = new core.List(this[_table].length * 2);
+        let split = this[_table].length - this[_head];
+        newTable.setRange(0, split, this[_table], this[_head]);
+        newTable.setRange(split, split + this[_head], this[_table], 0);
+        this[_head] = 0;
+        this[_tail] = this[_table].length;
+        this[_table] = newTable;
       }
-      _writeToList(target) {
+      [_writeToList](target) {
         dart.assert(target.length >= this.length);
-        if (this._head <= this._tail) {
-          let length = this._tail - this._head;
-          target.setRange(0, length, this._table, this._head);
+        if (this[_head] <= this[_tail]) {
+          let length = this[_tail] - this[_head];
+          target.setRange(0, length, this[_table], this[_head]);
           return length;
         } else {
-          let firstPartSize = this._table.length - this._head;
-          target.setRange(0, firstPartSize, this._table, this._head);
-          target.setRange(firstPartSize, firstPartSize + this._tail, this._table, 0);
-          return this._tail + firstPartSize;
+          let firstPartSize = this[_table].length - this[_head];
+          target.setRange(0, firstPartSize, this[_table], this[_head]);
+          target.setRange(firstPartSize, firstPartSize + this[_tail], this[_table], 0);
+          return this[_tail] + firstPartSize;
         }
       }
-      _preGrow(newElementCount) {
+      [_preGrow](newElementCount) {
         dart.assert(newElementCount >= this.length);
         newElementCount = newElementCount >> 1;
         let newCapacity = _nextPowerOf2(newElementCount);
         let newTable = new core.List(newCapacity);
-        this._tail = this._writeToList(newTable);
-        this._table = newTable;
-        this._head = 0;
+        this[_tail] = this[_writeToList](newTable);
+        this[_table] = newTable;
+        this[_head] = 0;
       }
     }
     dart.defineNamedConstructor(ListQueue, 'from');
@@ -3759,26 +3840,29 @@ var collection;
     return ListQueue;
   });
   let ListQueue = ListQueue$(dynamic);
+  let _queue = Symbol('_queue');
+  let _end = Symbol('_end');
+  let _position = Symbol('_position');
   let _ListQueueIterator$ = dart.generic(function(E) {
     class _ListQueueIterator extends dart.Object {
       _ListQueueIterator(queue) {
-        this._queue = queue;
-        this._end = queue._tail;
-        this._modificationCount = queue._modificationCount;
-        this._position = queue._head;
-        this._current = dart.as(null, E);
+        this[_queue] = queue;
+        this[_end] = queue[_tail];
+        this[_modificationCount] = queue[_modificationCount];
+        this[_position] = queue[_head];
+        this[_current] = dart.as(null, E);
       }
       get current() {
-        return this._current;
+        return this[_current];
       }
       moveNext() {
-        this._queue._checkModification(this._modificationCount);
-        if (this._position === this._end) {
-          this._current = dart.as(null, E);
+        this[_queue]._checkModification(this[_modificationCount]);
+        if (this[_position] === this[_end]) {
+          this[_current] = dart.as(null, E);
           return false;
         }
-        this._current = dart.as(this._queue._table.get(this._position), E);
-        this._position = this._position + 1 & this._queue._table.length - 1;
+        this[_current] = dart.as(this[_queue][_table].get(this[_position]), E);
+        this[_position] = this[_position] + 1 & this[_queue][_table].length - 1;
         return true;
       }
     }
@@ -4061,28 +4145,38 @@ var collection;
     return _SplayTreeMapNode;
   });
   let _SplayTreeMapNode = _SplayTreeMapNode$(dynamic, dynamic);
+  let _dummy = Symbol('_dummy');
+  let _root = Symbol('_root');
+  let _count = Symbol('_count');
+  let _splayCount = Symbol('_splayCount');
+  let _splay = Symbol('_splay');
+  let _compare = Symbol('_compare');
+  let _splayMin = Symbol('_splayMin');
+  let _splayMax = Symbol('_splayMax');
+  let _addNewRoot = Symbol('_addNewRoot');
+  let _clear = Symbol('_clear');
   let _SplayTree$ = dart.generic(function(K) {
     class _SplayTree extends dart.Object {
       _SplayTree() {
-        this._dummy = new _SplayTreeNode(dart.as(null, K));
-        this._root = null;
-        this._count = 0;
-        this._modificationCount = 0;
-        this._splayCount = 0;
-      }
-      _splay(key) {
-        if (this._root === null)
+        this[_dummy] = new _SplayTreeNode(dart.as(null, K));
+        this[_root] = null;
+        this[_count] = 0;
+        this[_modificationCount] = 0;
+        this[_splayCount] = 0;
+      }
+      [_splay](key) {
+        if (this[_root] === null)
           return -1;
-        let left = this._dummy;
-        let right = this._dummy;
-        let current = this._root;
+        let left = this[_dummy];
+        let right = this[_dummy];
+        let current = this[_root];
         let comp = null;
         while (true) {
-          comp = this._compare(current.key, key);
+          comp = this[_compare](current.key, key);
           if (comp > 0) {
             if (current.left === null)
               break;
-            comp = this._compare(current.left.key, key);
+            comp = this[_compare](current.left.key, key);
             if (comp > 0) {
               let tmp = current.left;
               current.left = tmp.right;
@@ -4097,7 +4191,7 @@ var collection;
           } else if (comp < 0) {
             if (current.right === null)
               break;
-            comp = this._compare(current.right.key, key);
+            comp = this[_compare](current.right.key, key);
             if (comp < 0) {
               let tmp = current.right;
               current.right = tmp.left;
@@ -4115,15 +4209,15 @@ var collection;
         }
         left.right = current.left;
         right.left = current.right;
-        current.left = this._dummy.right;
-        current.right = this._dummy.left;
-        this._root = current;
-        this._dummy.right = null;
-        this._dummy.left = null;
-        this._splayCount++;
+        current.left = this[_dummy].right;
+        current.right = this[_dummy].left;
+        this[_root] = current;
+        this[_dummy].right = null;
+        this[_dummy].left = null;
+        this[_splayCount]++;
         return comp;
       }
-      _splayMin(node) {
+      [_splayMin](node) {
         let current = node;
         while (current.left !== null) {
           let left = current.left;
@@ -4133,7 +4227,7 @@ var collection;
         }
         return dart.as(current, _SplayTreeNode$(K));
       }
-      _splayMax(node) {
+      [_splayMax](node) {
         let current = node;
         while (current.right !== null) {
           let right = current.right;
@@ -4143,58 +4237,58 @@ var collection;
         }
         return dart.as(current, _SplayTreeNode$(K));
       }
-      _remove(key) {
-        if (this._root === null)
+      [_remove](key) {
+        if (this[_root] === null)
           return null;
-        let comp = this._splay(key);
+        let comp = this[_splay](key);
         if (comp !== 0)
           return null;
-        let result = this._root;
-        this._count--;
-        if (this._root.left === null) {
-          this._root = this._root.right;
+        let result = this[_root];
+        this[_count]--;
+        if (this[_root].left === null) {
+          this[_root] = this[_root].right;
         } else {
-          let right = this._root.right;
-          this._root = this._splayMax(this._root.left);
-          this._root.right = right;
+          let right = this[_root].right;
+          this[_root] = this[_splayMax](this[_root].left);
+          this[_root].right = right;
         }
-        this._modificationCount++;
+        this[_modificationCount]++;
         return result;
       }
-      _addNewRoot(node, comp) {
-        this._count++;
-        this._modificationCount++;
-        if (this._root === null) {
-          this._root = node;
+      [_addNewRoot](node, comp) {
+        this[_count]++;
+        this[_modificationCount]++;
+        if (this[_root] === null) {
+          this[_root] = node;
           return;
         }
         if (comp < 0) {
-          node.left = this._root;
-          node.right = this._root.right;
-          this._root.right = null;
+          node.left = this[_root];
+          node.right = this[_root].right;
+          this[_root].right = null;
         } else {
-          node.right = this._root;
-          node.left = this._root.left;
-          this._root.left = null;
+          node.right = this[_root];
+          node.left = this[_root].left;
+          this[_root].left = null;
         }
-        this._root = node;
+        this[_root] = node;
       }
-      get _first() {
-        if (this._root === null)
+      get [_first]() {
+        if (this[_root] === null)
           return null;
-        this._root = this._splayMin(this._root);
-        return this._root;
+        this[_root] = this[_splayMin](this[_root]);
+        return this[_root];
       }
-      get _last() {
-        if (this._root === null)
+      get [_last]() {
+        if (this[_root] === null)
           return null;
-        this._root = this._splayMax(this._root);
-        return this._root;
+        this[_root] = this[_splayMax](this[_root]);
+        return this[_root];
       }
-      _clear() {
-        this._root = null;
-        this._count = 0;
-        this._modificationCount++;
+      [_clear]() {
+        this[_root] = null;
+        this[_count] = 0;
+        this[_modificationCount]++;
       }
     }
     return _SplayTree;
@@ -4209,6 +4303,7 @@ var collection;
     return _TypeTest;
   });
   let _TypeTest = _TypeTest$(dynamic);
+  let _comparator = Symbol('_comparator');
   let SplayTreeMap$ = dart.generic(function(K, V) {
     class SplayTreeMap extends _SplayTree$(K) {
       SplayTreeMap(compare, isValidKey) {
@@ -4216,8 +4311,8 @@ var collection;
           compare = null;
         if (isValidKey === void 0)
           isValidKey = null;
-        this._comparator = dart.as(compare === null ? core.Comparable.compare : compare, core.Comparator);
-        this._validKey = dart.as(isValidKey !== null ? isValidKey : (v) => dart.is(v, K), _Predicate);
+        this[_comparator] = dart.as(compare === null ? core.Comparable.compare : compare, core.Comparator);
+        this[_validKey] = dart.as(isValidKey !== null ? isValidKey : (v) => dart.is(v, K), _Predicate);
         super._SplayTree();
       }
       SplayTreeMap$from(other, compare, isValidKey) {
@@ -4249,32 +4344,32 @@ var collection;
         Maps._fillMapWithIterables(map, keys, values);
         return map;
       }
-      _compare(key1, key2) {
-        return this._comparator(key1, key2);
+      [_compare](key1, key2) {
+        return this[_comparator](key1, key2);
       }
       SplayTreeMap$_internal() {
-        this._comparator = null;
-        this._validKey = null;
+        this[_comparator] = null;
+        this[_validKey] = null;
         super._SplayTree();
       }
       get(key) {
         if (key === null)
           throw new core.ArgumentError(key);
-        if (!dart.notNull(this._validKey(key)))
+        if (!dart.notNull(this[_validKey](key)))
           return dart.as(null, V);
-        if (this._root !== null) {
-          let comp = this._splay(dart.as(key, K));
+        if (this[_root] !== null) {
+          let comp = this[_splay](dart.as(key, K));
           if (comp === 0) {
-            let mapRoot = dart.as(this._root, _SplayTreeMapNode);
+            let mapRoot = dart.as(this[_root], _SplayTreeMapNode);
             return dart.as(mapRoot.value, V);
           }
         }
         return dart.as(null, V);
       }
       remove(key) {
-        if (!dart.notNull(this._validKey(key)))
+        if (!dart.notNull(this[_validKey](key)))
           return dart.as(null, V);
-        let mapRoot = dart.as(this._remove(dart.as(key, K)), _SplayTreeMapNode);
+        let mapRoot = dart.as(this[_remove](dart.as(key, K)), _SplayTreeMapNode);
         if (mapRoot !== null)
           return dart.as(mapRoot.value, V);
         return dart.as(null, V);
@@ -4282,33 +4377,33 @@ var collection;
       set(key, value) {
         if (key === null)
           throw new core.ArgumentError(key);
-        let comp = this._splay(key);
+        let comp = this[_splay](key);
         if (comp === 0) {
-          let mapRoot = dart.as(this._root, _SplayTreeMapNode);
+          let mapRoot = dart.as(this[_root], _SplayTreeMapNode);
           mapRoot.value = value;
           return;
         }
-        this._addNewRoot(dart.as(new _SplayTreeMapNode(key, value), _SplayTreeNode$(K)), comp);
+        this[_addNewRoot](dart.as(new _SplayTreeMapNode(key, value), _SplayTreeNode$(K)), comp);
       }
       putIfAbsent(key, ifAbsent) {
         if (key === null)
           throw new core.ArgumentError(key);
-        let comp = this._splay(key);
+        let comp = this[_splay](key);
         if (comp === 0) {
-          let mapRoot = dart.as(this._root, _SplayTreeMapNode);
+          let mapRoot = dart.as(this[_root], _SplayTreeMapNode);
           return dart.as(mapRoot.value, V);
         }
-        let modificationCount = this._modificationCount;
-        let splayCount = this._splayCount;
+        let modificationCount = this[_modificationCount];
+        let splayCount = this[_splayCount];
         let value = ifAbsent();
-        if (modificationCount !== this._modificationCount) {
+        if (modificationCount !== this[_modificationCount]) {
           throw new core.ConcurrentModificationError(this);
         }
-        if (splayCount !== this._splayCount) {
-          comp = this._splay(key);
+        if (splayCount !== this[_splayCount]) {
+          comp = this[_splay](key);
           dart.assert(comp !== 0);
         }
-        this._addNewRoot(dart.as(new _SplayTreeMapNode(key, value), _SplayTreeNode$(K)), comp);
+        this[_addNewRoot](dart.as(new _SplayTreeMapNode(key, value), _SplayTreeNode$(K)), comp);
         return value;
       }
       addAll(other) {
@@ -4317,7 +4412,7 @@ var collection;
         }).bind(this));
       }
       get isEmpty() {
-        return this._root === null;
+        return this[_root] === null;
       }
       get isNotEmpty() {
         return !dart.notNull(this.isEmpty);
@@ -4330,23 +4425,23 @@ var collection;
         }
       }
       get length() {
-        return this._count;
+        return this[_count];
       }
       clear() {
-        this._clear();
+        this[_clear]();
       }
       containsKey(key) {
-        return dart.notNull(this._validKey(key)) && dart.notNull(this._splay(dart.as(key, K)) === 0);
+        return dart.notNull(this[_validKey](key)) && dart.notNull(this[_splay](dart.as(key, K)) === 0);
       }
       containsValue(value) {
         let found = false;
-        let initialSplayCount = this._splayCount;
+        let initialSplayCount = this[_splayCount];
         // Function visit: (_SplayTreeMapNode<dynamic, dynamic>) → bool
         function visit(node) {
           while (node !== null) {
             if (dart.equals(node.value, value))
               return true;
-            if (initialSplayCount !== this._splayCount) {
+            if (initialSplayCount !== this[_splayCount]) {
               throw new core.ConcurrentModificationError(this);
             }
             if (dart.notNull(node.right !== null) && dart.notNull(visit(dart.as(node.right, _SplayTreeMapNode))))
@@ -4355,7 +4450,7 @@ var collection;
           }
           return false;
         }
-        return visit(dart.as(this._root, _SplayTreeMapNode));
+        return visit(dart.as(this[_root], _SplayTreeMapNode));
       }
       get keys() {
         return new _SplayTreeKeyIterable(this);
@@ -4367,24 +4462,24 @@ var collection;
         return Maps.mapToString(this);
       }
       firstKey() {
-        if (this._root === null)
+        if (this[_root] === null)
           return dart.as(null, K);
-        return dart.as(this._first.key, K);
+        return dart.as(this[_first].key, K);
       }
       lastKey() {
-        if (this._root === null)
+        if (this[_root] === null)
           return dart.as(null, K);
-        return dart.as(this._last.key, K);
+        return dart.as(this[_last].key, K);
       }
       lastKeyBefore(key) {
         if (key === null)
           throw new core.ArgumentError(key);
-        if (this._root === null)
+        if (this[_root] === null)
           return dart.as(null, K);
-        let comp = this._splay(key);
+        let comp = this[_splay](key);
         if (comp < 0)
-          return this._root.key;
-        let node = this._root.left;
+          return this[_root].key;
+        let node = this[_root].left;
         if (node === null)
           return dart.as(null, K);
         while (node.right !== null) {
@@ -4395,12 +4490,12 @@ var collection;
       firstKeyAfter(key) {
         if (key === null)
           throw new core.ArgumentError(key);
-        if (this._root === null)
+        if (this[_root] === null)
           return dart.as(null, K);
-        let comp = this._splay(key);
+        let comp = this[_splay](key);
         if (comp > 0)
-          return this._root.key;
-        let node = this._root.right;
+          return this[_root].key;
+        let node = this[_root].right;
         if (node === null)
           return dart.as(null, K);
         while (node.left !== null) {
@@ -4416,67 +4511,73 @@ var collection;
     return SplayTreeMap;
   });
   let SplayTreeMap = SplayTreeMap$(dynamic, dynamic);
+  let _workList = Symbol('_workList');
+  let _tree = Symbol('_tree');
+  let _currentNode = Symbol('_currentNode');
+  let _findLeftMostDescendent = Symbol('_findLeftMostDescendent');
+  let _getValue = Symbol('_getValue');
+  let _rebuildWorkList = Symbol('_rebuildWorkList');
   let _SplayTreeIterator$ = dart.generic(function(T) {
     class _SplayTreeIterator extends dart.Object {
       _SplayTreeIterator(tree) {
-        this._workList = new List.from([]);
-        this._tree = tree;
-        this._modificationCount = tree._modificationCount;
-        this._splayCount = tree._splayCount;
-        this._currentNode = null;
-        this._findLeftMostDescendent(tree._root);
+        this[_workList] = new List.from([]);
+        this[_tree] = tree;
+        this[_modificationCount] = tree[_modificationCount];
+        this[_splayCount] = tree[_splayCount];
+        this[_currentNode] = null;
+        this[_findLeftMostDescendent](tree[_root]);
       }
       _SplayTreeIterator$startAt(tree, startKey) {
-        this._workList = new List.from([]);
-        this._tree = tree;
-        this._modificationCount = tree._modificationCount;
-        this._splayCount = dart.as(null, core.int);
-        this._currentNode = null;
-        if (tree._root === null)
+        this[_workList] = new List.from([]);
+        this[_tree] = tree;
+        this[_modificationCount] = tree[_modificationCount];
+        this[_splayCount] = dart.as(null, core.int);
+        this[_currentNode] = null;
+        if (tree[_root] === null)
           return;
         let compare = tree._splay(startKey);
-        this._splayCount = tree._splayCount;
+        this[_splayCount] = tree[_splayCount];
         if (compare < 0) {
-          this._findLeftMostDescendent(tree._root.right);
+          this[_findLeftMostDescendent](tree[_root].right);
         } else {
-          this._workList.add(tree._root);
+          this[_workList].add(tree[_root]);
         }
       }
       get current() {
-        if (this._currentNode === null)
+        if (this[_currentNode] === null)
           return dart.as(null, T);
-        return this._getValue(this._currentNode);
+        return this[_getValue](this[_currentNode]);
       }
-      _findLeftMostDescendent(node) {
+      [_findLeftMostDescendent](node) {
         while (node !== null) {
-          this._workList.add(node);
+          this[_workList].add(node);
           node = node.left;
         }
       }
-      _rebuildWorkList(currentNode) {
-        dart.assert(!dart.notNull(this._workList.isEmpty));
-        this._workList.clear();
+      [_rebuildWorkList](currentNode) {
+        dart.assert(!dart.notNull(this[_workList].isEmpty));
+        this[_workList].clear();
         if (currentNode === null) {
-          this._findLeftMostDescendent(this._tree._root);
+          this[_findLeftMostDescendent](this[_tree][_root]);
         } else {
-          this._tree._splay(currentNode.key);
-          this._findLeftMostDescendent(this._tree._root.right);
-          dart.assert(!dart.notNull(this._workList.isEmpty));
+          this[_tree]._splay(currentNode.key);
+          this[_findLeftMostDescendent](this[_tree][_root].right);
+          dart.assert(!dart.notNull(this[_workList].isEmpty));
         }
       }
       moveNext() {
-        if (this._modificationCount !== this._tree._modificationCount) {
-          throw new core.ConcurrentModificationError(this._tree);
+        if (this[_modificationCount] !== this[_tree][_modificationCount]) {
+          throw new core.ConcurrentModificationError(this[_tree]);
         }
-        if (this._workList.isEmpty) {
-          this._currentNode = null;
+        if (this[_workList].isEmpty) {
+          this[_currentNode] = null;
           return false;
         }
-        if (dart.notNull(this._tree._splayCount !== this._splayCount) && dart.notNull(this._currentNode !== null)) {
-          this._rebuildWorkList(this._currentNode);
+        if (dart.notNull(this[_tree][_splayCount] !== this[_splayCount]) && dart.notNull(this[_currentNode] !== null)) {
+          this[_rebuildWorkList](this[_currentNode]);
         }
-        this._currentNode = this._workList.removeLast();
-        this._findLeftMostDescendent(this._currentNode.right);
+        this[_currentNode] = this[_workList].removeLast();
+        this[_findLeftMostDescendent](this[_currentNode].right);
         return true;
       }
     }
@@ -4486,24 +4587,24 @@ var collection;
   let _SplayTreeIterator = _SplayTreeIterator$(dynamic);
   let _SplayTreeKeyIterable$ = dart.generic(function(K) {
     class _SplayTreeKeyIterable extends IterableBase$(K) {
-      _SplayTreeKeyIterable(_tree) {
-        this._tree = _tree;
+      _SplayTreeKeyIterable($_tree) {
+        this[_tree] = $_tree;
         super.IterableBase();
       }
       get length() {
-        return this._tree._count;
+        return this[_tree][_count];
       }
       get isEmpty() {
-        return this._tree._count === 0;
+        return this[_tree][_count] === 0;
       }
       get iterator() {
-        return new _SplayTreeKeyIterator(this._tree);
+        return new _SplayTreeKeyIterator(this[_tree]);
       }
       toSet() {
-        let setOrMap = this._tree;
-        let set = new SplayTreeSet(dart.as(setOrMap._comparator, dart.throw_("Unimplemented type (K, K) → int")), dart.as(setOrMap._validKey, dart.throw_("Unimplemented type (dynamic) → bool")));
-        set._count = this._tree._count;
-        set._root = set._copyNode(this._tree._root);
+        let setOrMap = this[_tree];
+        let set = new SplayTreeSet(dart.as(setOrMap[_comparator], dart.throw_("Unimplemented type (K, K) → int")), dart.as(setOrMap[_validKey], dart.throw_("Unimplemented type (dynamic) → bool")));
+        set[_count] = this[_tree][_count];
+        set[_root] = set._copyNode(this[_tree][_root]);
         return set;
       }
     }
@@ -4512,18 +4613,18 @@ var collection;
   let _SplayTreeKeyIterable = _SplayTreeKeyIterable$(dynamic);
   let _SplayTreeValueIterable$ = dart.generic(function(K, V) {
     class _SplayTreeValueIterable extends IterableBase$(V) {
-      _SplayTreeValueIterable(_map) {
-        this._map = _map;
+      _SplayTreeValueIterable($_map) {
+        this[_map] = $_map;
         super.IterableBase();
       }
       get length() {
-        return this._map._count;
+        return this[_map][_count];
       }
       get isEmpty() {
-        return this._map._count === 0;
+        return this[_map][_count] === 0;
       }
       get iterator() {
-        return new _SplayTreeValueIterator(this._map);
+        return new _SplayTreeValueIterator(this[_map]);
       }
     }
     return _SplayTreeValueIterable;
@@ -4534,7 +4635,7 @@ var collection;
       _SplayTreeKeyIterator(map) {
         super._SplayTreeIterator(map);
       }
-      _getValue(node) {
+      [_getValue](node) {
         return dart.as(node.key, K);
       }
     }
@@ -4546,7 +4647,7 @@ var collection;
       _SplayTreeValueIterator(map) {
         super._SplayTreeIterator(map);
       }
-      _getValue(node) {
+      [_getValue](node) {
         return dart.as(node.value, V);
       }
     }
@@ -4561,7 +4662,7 @@ var collection;
       _SplayTreeNodeIterator$startAt(tree, startKey) {
         super._SplayTreeIterator$startAt(tree, startKey);
       }
-      _getValue(node) {
+      [_getValue](node) {
         return dart.as(node, _SplayTreeNode$(K));
       }
     }
@@ -4569,6 +4670,8 @@ var collection;
     return _SplayTreeNodeIterator;
   });
   let _SplayTreeNodeIterator = _SplayTreeNodeIterator$(dynamic);
+  let _clone = Symbol('_clone');
+  let _copyNode = Symbol('_copyNode');
   let SplayTreeSet$ = dart.generic(function(E) {
     class SplayTreeSet extends dart.mixin(_SplayTree$(E), IterableMixin$(E), SetMixin$(E)) {
       SplayTreeSet(compare, isValidKey) {
@@ -4576,8 +4679,8 @@ var collection;
           compare = null;
         if (isValidKey === void 0)
           isValidKey = null;
-        this._comparator = dart.as(compare === null ? core.Comparable.compare : compare, core.Comparator);
-        this._validKey = dart.as(isValidKey !== null ? isValidKey : (v) => dart.is(v, E), _Predicate);
+        this[_comparator] = dart.as(compare === null ? core.Comparable.compare : compare, core.Comparator);
+        this[_validKey] = dart.as(isValidKey !== null ? isValidKey : (v) => dart.is(v, E), _Predicate);
         super._SplayTree();
       }
       SplayTreeSet$from(elements, compare, isValidKey) {
@@ -4591,93 +4694,93 @@ var collection;
         }
         return result;
       }
-      _compare(e1, e2) {
-        return this._comparator(e1, e2);
+      [_compare](e1, e2) {
+        return this[_comparator](e1, e2);
       }
       get iterator() {
         return new _SplayTreeKeyIterator(this);
       }
       get length() {
-        return this._count;
+        return this[_count];
       }
       get isEmpty() {
-        return this._root === null;
+        return this[_root] === null;
       }
       get isNotEmpty() {
-        return this._root !== null;
+        return this[_root] !== null;
       }
       get first() {
-        if (this._count === 0)
+        if (this[_count] === 0)
           throw _internal.IterableElementError.noElement();
-        return dart.as(this._first.key, E);
+        return dart.as(this[_first].key, E);
       }
       get last() {
-        if (this._count === 0)
+        if (this[_count] === 0)
           throw _internal.IterableElementError.noElement();
-        return dart.as(this._last.key, E);
+        return dart.as(this[_last].key, E);
       }
       get single() {
-        if (this._count === 0)
+        if (this[_count] === 0)
           throw _internal.IterableElementError.noElement();
-        if (this._count > 1)
+        if (this[_count] > 1)
           throw _internal.IterableElementError.tooMany();
-        return this._root.key;
+        return this[_root].key;
       }
       contains(object) {
-        return dart.notNull(this._validKey(object)) && dart.notNull(this._splay(dart.as(object, E)) === 0);
+        return dart.notNull(this[_validKey](object)) && dart.notNull(this[_splay](dart.as(object, E)) === 0);
       }
       add(element) {
-        let compare = this._splay(element);
+        let compare = this[_splay](element);
         if (compare === 0)
           return false;
-        this._addNewRoot(dart.as(new _SplayTreeNode(element), _SplayTreeNode$(E)), compare);
+        this[_addNewRoot](dart.as(new _SplayTreeNode(element), _SplayTreeNode$(E)), compare);
         return true;
       }
       remove(object) {
-        if (!dart.notNull(this._validKey(object)))
+        if (!dart.notNull(this[_validKey](object)))
           return false;
-        return this._remove(dart.as(object, E)) !== null;
+        return this[_remove](dart.as(object, E)) !== null;
       }
       addAll(elements) {
         for (let element of elements) {
-          let compare = this._splay(element);
+          let compare = this[_splay](element);
           if (compare !== 0) {
-            this._addNewRoot(dart.as(new _SplayTreeNode(element), _SplayTreeNode$(E)), compare);
+            this[_addNewRoot](dart.as(new _SplayTreeNode(element), _SplayTreeNode$(E)), compare);
           }
         }
       }
       removeAll(elements) {
         for (let element of elements) {
-          if (this._validKey(element))
-            this._remove(dart.as(element, E));
+          if (this[_validKey](element))
+            this[_remove](dart.as(element, E));
         }
       }
       retainAll(elements) {
-        let retainSet = new SplayTreeSet(this._comparator, this._validKey);
-        let modificationCount = this._modificationCount;
+        let retainSet = new SplayTreeSet(this[_comparator], this[_validKey]);
+        let modificationCount = this[_modificationCount];
         for (let object of elements) {
-          if (modificationCount !== this._modificationCount) {
+          if (modificationCount !== this[_modificationCount]) {
             throw new core.ConcurrentModificationError(this);
           }
-          if (dart.notNull(this._validKey(object)) && dart.notNull(this._splay(dart.as(object, E)) === 0))
-            retainSet.add(this._root.key);
+          if (dart.notNull(this[_validKey](object)) && dart.notNull(this[_splay](dart.as(object, E)) === 0))
+            retainSet.add(this[_root].key);
         }
-        if (retainSet._count !== this._count) {
-          this._root = retainSet._root;
-          this._count = retainSet._count;
-          this._modificationCount++;
+        if (retainSet[_count] !== this[_count]) {
+          this[_root] = retainSet[_root];
+          this[_count] = retainSet[_count];
+          this[_modificationCount]++;
         }
       }
       lookup(object) {
-        if (!dart.notNull(this._validKey(object)))
+        if (!dart.notNull(this[_validKey](object)))
           return dart.as(null, E);
-        let comp = this._splay(dart.as(object, E));
+        let comp = this[_splay](dart.as(object, E));
         if (comp !== 0)
           return dart.as(null, E);
-        return this._root.key;
+        return this[_root].key;
       }
       intersection(other) {
-        let result = new SplayTreeSet(this._comparator, this._validKey);
+        let result = new SplayTreeSet(this[_comparator], this[_validKey]);
         for (let element of this) {
           if (other.contains(element))
             result.add(element);
@@ -4685,7 +4788,7 @@ var collection;
         return result;
       }
       difference(other) {
-        let result = new SplayTreeSet(this._comparator, this._validKey);
+        let result = new SplayTreeSet(this[_comparator], this[_validKey]);
         for (let element of this) {
           if (!dart.notNull(other.contains(element)))
             result.add(element);
@@ -4696,28 +4799,28 @@ var collection;
         return ((_) => {
           _.addAll(other);
           return _;
-        }).bind(this)(this._clone());
+        }).bind(this)(this[_clone]());
       }
-      _clone() {
-        let set = new SplayTreeSet(this._comparator, this._validKey);
-        set._count = this._count;
-        set._root = this._copyNode(this._root);
+      [_clone]() {
+        let set = new SplayTreeSet(this[_comparator], this[_validKey]);
+        set[_count] = this[_count];
+        set[_root] = this[_copyNode](this[_root]);
         return set;
       }
-      _copyNode(node) {
+      [_copyNode](node) {
         if (node === null)
           return null;
         return ((_) => {
-          _.left = this._copyNode(node.left);
-          _.right = this._copyNode(node.right);
+          _.left = this[_copyNode](node.left);
+          _.right = this[_copyNode](node.right);
           return _;
         }).bind(this)(new _SplayTreeNode(node.key));
       }
       clear() {
-        this._clear();
+        this[_clear]();
       }
       toSet() {
-        return this._clone();
+        return this[_clone]();
       }
       toString() {
         return IterableBase.iterableToFullString(this, '{', '}');