Add a few more known non-null cases

lib/runtime/dart/collection.js

 dart_library.library('dart/collection', null, /* Imports */[
   'dart/_runtime',
   'dart/core'
 ], /* Lazy imports */[
   'dart/_internal',
   'dart/_js_helper',
   'dart/math'
 ], function(exports, dart, core, _internal, _js_helper, math) {
   'use strict';
   let dartx = dart.dartx;
@@ skipping 42 matching lines @@
         let equals = opts && 'equals' in opts ? opts.equals : null;
         let hashCode = opts && 'hashCode' in opts ? opts.hashCode : null;
         let isValidKey = opts && 'isValidKey' in opts ? opts.isValidKey : null;
         if (isValidKey == null) {
           if (hashCode == null) {
             if (equals == null) {
               return new (_HashMap$(K, V))();
             }
             hashCode = _defaultHashCode;
           } else {
-            if (dart.notNull(core.identical(core.identityHashCode, hashCode)) && dart.notNull(core.identical(core.identical, equals))) {
+            if (core.identical(core.identityHashCode, hashCode) && core.identical(core.identical, equals)) {
               return new (_IdentityHashMap$(K, V))();
             }
             if (equals == null) {
               equals = _defaultEquals;
             }
           }
         } else {
           if (hashCode == null) {
             hashCode = _defaultHashCode;
           }
@@ skipping 185 matching lines @@
           do {
             buffer.write(`${iterator.current}`);
           } while (dart.notNull(iterator.moveNext()));
         } else {
           buffer.write(`${iterator.current}`);
           while (dart.notNull(iterator.moveNext())) {
             buffer.write(separator);
             buffer.write(`${iterator.current}`);
           }
         }
-        return dart.toString(buffer);
+        return buffer.toString();
       }
       any(test) {
         dart.as(test, dart.functionType(core.bool, [E]));
         for (let element of this) {
           if (dart.notNull(test(element))) return true;
         }
         return false;
       }
       take(n) {
         return _internal.TakeIterable$(E).new(this, n);
@@ skipping 196 matching lines @@
         let equals = opts && 'equals' in opts ? opts.equals : null;
         let hashCode = opts && 'hashCode' in opts ? opts.hashCode : null;
         let isValidKey = opts && 'isValidKey' in opts ? opts.isValidKey : null;
         if (isValidKey == null) {
           if (hashCode == null) {
             if (equals == null) {
               return new (_HashSet$(E))();
             }
             hashCode = _defaultHashCode;
           } else {
-            if (dart.notNull(core.identical(core.identityHashCode, hashCode)) && dart.notNull(core.identical(core.identical, equals))) {
+            if (core.identical(core.identityHashCode, hashCode) && core.identical(core.identical, equals)) {
               return new (_IdentityHashSet$(E))();
             }
             if (equals == null) {
               equals = _defaultEquals;
             }
           }
         } else {
           if (hashCode == null) {
             hashCode = _defaultHashCode;
           }
@@ skipping 87 matching lines @@
           do {
             buffer.write(`${iterator.current}`);
           } while (dart.notNull(iterator.moveNext()));
         } else {
           buffer.write(`${iterator.current}`);
           while (dart.notNull(iterator.moveNext())) {
             buffer.write(separator);
             buffer.write(`${iterator.current}`);
           }
         }
-        return dart.toString(buffer);
+        return buffer.toString();
       }
       any(f) {
         dart.as(f, dart.functionType(core.bool, [E]));
         for (let element of this) {
           if (dart.notNull(f(element))) return true;
         }
         return false;
       }
       toList(opts) {
         let growable = opts && 'growable' in opts ? opts.growable : true;
@@ skipping 233 matching lines @@
           do {
             buffer.write(`${iterator.current}`);
           } while (dart.notNull(iterator.moveNext()));
         } else {
           buffer.write(`${iterator.current}`);
           while (dart.notNull(iterator.moveNext())) {
             buffer.write(separator);
             buffer.write(`${iterator.current}`);
           }
         }
-        return dart.toString(buffer);
+        return buffer.toString();
       }
       any(f) {
         dart.as(f, dart.functionType(core.bool, [E]));
         for (let element of this) {
           if (dart.notNull(f(element))) return true;
         }
         return false;
       }
       toList(opts) {
         let growable = opts && 'growable' in opts ? opts.growable : true;
@@ skipping 143 matching lines @@
         }
         let buffer = new core.StringBuffer(leftDelimiter);
         IterableBase$()._toStringVisiting[dartx.add](iterable);
         try {
           buffer.writeAll(iterable, ", ");
         } finally {
           dart.assert(core.identical(IterableBase$()._toStringVisiting[dartx.last], iterable));
           IterableBase$()._toStringVisiting[dartx.removeLast]();
         }
         buffer.write(rightDelimiter);
-        return dart.toString(buffer);
+        return buffer.toString();
       }
       static _isToStringVisiting(o) {
         for (let i = 0; i < dart.notNull(IterableBase$()._toStringVisiting[dartx.length]); i++) {
-          if (dart.notNull(core.identical(o, IterableBase$()._toStringVisiting[dartx.get](i)))) return true;
+          if (core.identical(o, IterableBase$()._toStringVisiting[dartx.get](i))) return true;
         }
         return false;
       }
       static _iterablePartsToStrings(iterable, parts) {
         let LENGTH_LIMIT = 80;
         let HEAD_COUNT = 3;
         let TAIL_COUNT = 2;
         let MAX_COUNT = 100;
         let OVERHEAD = 2;
         let ELLIPSIS_SIZE = 3;
@@ skipping 186 matching lines @@
         let equals = opts && 'equals' in opts ? opts.equals : null;
         let hashCode = opts && 'hashCode' in opts ? opts.hashCode : null;
         let isValidKey = opts && 'isValidKey' in opts ? opts.isValidKey : null;
         if (isValidKey == null) {
           if (hashCode == null) {
             if (equals == null) {
               return new (_LinkedHashMap$(K, V))();
             }
             hashCode = _defaultHashCode;
           } else {
-            if (dart.notNull(core.identical(core.identityHashCode, hashCode)) && dart.notNull(core.identical(core.identical, equals))) {
+            if (core.identical(core.identityHashCode, hashCode) && core.identical(core.identical, equals)) {
               return new (_LinkedIdentityHashMap$(K, V))();
             }
             if (equals == null) {
               equals = _defaultEquals;
             }
           }
         } else {
           if (hashCode == null) {
             hashCode = _defaultHashCode;
           }
@@ skipping 53 matching lines @@
         let equals = opts && 'equals' in opts ? opts.equals : null;
         let hashCode = opts && 'hashCode' in opts ? opts.hashCode : null;
         let isValidKey = opts && 'isValidKey' in opts ? opts.isValidKey : null;
         if (isValidKey == null) {
           if (hashCode == null) {
             if (equals == null) {
               return new (_LinkedHashSet$(E))();
             }
             hashCode = _defaultHashCode;
           } else {
-            if (dart.notNull(core.identical(core.identityHashCode, hashCode)) && dart.notNull(core.identical(core.identical, equals))) {
+            if (core.identical(core.identityHashCode, hashCode) && core.identical(core.identical, equals)) {
               return new (_LinkedIdentityHashSet$(E))();
             }
             if (equals == null) {
               equals = _defaultEquals;
             }
           }
         } else {
           if (hashCode == null) {
             hashCode = _defaultHashCode;
           }
@@ skipping 65 matching lines @@
       }
       get iterator() {
         return new (_LinkedListIterator$(E))(this);
       }
       get length() {
         return this[_length];
       }
       clear() {
         this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
         let next = this[_next];
-        while (!dart.notNull(core.identical(next, this))) {
+        while (!core.identical(next, this)) {
           let entry = dart.as(next, E);
           next = entry[_next];
           entry[_next] = entry[_previous] = entry[_list] = null;
         }
         this[_next] = this[_previous] = this;
         this[_length] = 0;
       }
       get first() {
-        if (dart.notNull(core.identical(this[_next], this))) {
+        if (core.identical(this[_next], this)) {
           dart.throw(new core.StateError('No such element'));
         }
         return dart.as(this[_next], E);
       }
       get last() {
-        if (dart.notNull(core.identical(this[_previous], this))) {
+        if (core.identical(this[_previous], this)) {
           dart.throw(new core.StateError('No such element'));
         }
         return dart.as(this[_previous], E);
       }
       get single() {
-        if (dart.notNull(core.identical(this[_previous], this))) {
+        if (core.identical(this[_previous], this)) {
           dart.throw(new core.StateError('No such element'));
         }
-        if (!dart.notNull(core.identical(this[_previous], this[_next]))) {
+        if (!core.identical(this[_previous], this[_next])) {
           dart.throw(new core.StateError('Too many elements'));
         }
         return dart.as(this[_next], E);
       }
       forEach(action) {
         dart.as(action, dart.functionType(dart.void, [E]));
         let modificationCount = this[_modificationCount];
         let current = this[_next];
-        while (!dart.notNull(core.identical(current, this))) {
+        while (!core.identical(current, this)) {
           action(dart.as(current, E));
           if (modificationCount != this[_modificationCount]) {
             dart.throw(new core.ConcurrentModificationError(this));
           }
           current = current[_next];
         }
       }
       get isEmpty() {
         return this[_length] == 0;
       }
@@ skipping 53 matching lines @@
       _LinkedListIterator(list) {
         this[_list] = list;
         this[_modificationCount] = list[_modificationCount];
         this[_next] = list[_next];
         this[_current] = null;
       }
       get current() {
         return this[_current];
       }
       moveNext() {
-        if (dart.notNull(core.identical(this[_next], this[_list]))) {
+        if (core.identical(this[_next], this[_list])) {
           this[_current] = null;
           return false;
         }
         if (this[_modificationCount] != this[_list][_modificationCount]) {
           dart.throw(new core.ConcurrentModificationError(this));
         }
         this[_current] = dart.as(this[_next], E);
         this[_next] = this[_next][_next];
         return true;
       }
@@ skipping 19 matching lines @@
         this[_next] = null;
         this[_previous] = null;
       }
       get list() {
         return this[_list];
       }
       unlink() {
         this[_list][_unlink](this);
       }
       get next() {
-        if (dart.notNull(core.identical(this[_next], this[_list]))) return null;
+        if (core.identical(this[_next], this[_list])) return null;
         let result = dart.as(this[_next], E);
         return result;
       }
       get previous() {
-        if (dart.notNull(core.identical(this[_previous], this[_list]))) return null;
+        if (core.identical(this[_previous], this[_list])) return null;
         return dart.as(this[_previous], E);
       }
       insertAfter(entry) {
         dart.as(entry, E);
         this[_list][_insertAfter](this, entry);
       }
       insertBefore(entry) {
         dart.as(entry, E);
         this[_list][_insertAfter](this[_previous], entry);
       }
@@ skipping 948 matching lines @@
           first = false;
           result.write(k);
           result.write(': ');
           result.write(v);
         }, dart.void, [dart.dynamic, dart.dynamic]));
         result.write('}');
       } finally {
         dart.assert(core.identical(IterableBase._toStringVisiting[dartx.last], m));
         IterableBase._toStringVisiting[dartx.removeLast]();
       }
-      return dart.toString(result);
+      return result.toString();
     }
     static _id(x) {
       return x;
     }
     static _fillMapWithMappedIterable(map, iterable, key, value) {
       if (key == null) key = Maps._id;
       if (value == null) value = Maps._id;
       for (let element of iterable) {
         map[dartx.set](dart.dcall(key, element), dart.dcall(value, element));
       }
@@ skipping 196 matching lines @@
         this[_elementCount] = dart.notNull(this[_elementCount]) - 1;
         return result;
       }
       removeFirst() {
         let result = this[_sentinel][_next].remove();
         this[_elementCount] = dart.notNull(this[_elementCount]) - 1;
         return result;
       }
       remove(o) {
         let entry = this[_sentinel][_next];
-        while (!dart.notNull(core.identical(entry, this[_sentinel]))) {
+        while (!core.identical(entry, this[_sentinel])) {
           if (dart.equals(entry.element, o)) {
             entry.remove();
             this[_elementCount] = dart.notNull(this[_elementCount]) - 1;
             return true;
           }
           entry = entry[_next];
         }
         return false;
       }
       [_filter](test, removeMatching) {
         dart.as(test, dart.functionType(core.bool, [E]));
         let entry = this[_sentinel][_next];
-        while (!dart.notNull(core.identical(entry, this[_sentinel]))) {
+        while (!core.identical(entry, this[_sentinel])) {
           let next = entry[_next];
-          if (dart.notNull(core.identical(removeMatching, test(entry.element)))) {
+          if (core.identical(removeMatching, test(entry.element))) {
             entry.remove();
             this[_elementCount] = dart.notNull(this[_elementCount]) - 1;
           }
           entry = next;
         }
       }
       removeWhere(test) {
         dart.as(test, dart.functionType(core.bool, [E]));
         this[_filter](test, true);
       }
       retainWhere(test) {
         dart.as(test, dart.functionType(core.bool, [E]));
         this[_filter](test, false);
       }
       get first() {
         return this[_sentinel][_next].element;
       }
       get last() {
         return this[_sentinel][_previous].element;
       }
       get single() {
-        if (dart.notNull(core.identical(this[_sentinel][_next], this[_sentinel][_previous]))) {
+        if (core.identical(this[_sentinel][_next], this[_sentinel][_previous])) {
           return this[_sentinel][_next].element;
         }
         dart.throw(_internal.IterableElementError.tooMany());
       }
       lastEntry() {
         return this[_sentinel].previousEntry();
       }
       firstEntry() {
         return this[_sentinel].nextEntry();
       }
       get isEmpty() {
         return core.identical(this[_sentinel][_next], this[_sentinel]);
       }
       clear() {
         this[_sentinel][_next] = this[_sentinel];
         this[_sentinel][_previous] = this[_sentinel];
         this[_elementCount] = 0;
       }
       forEachEntry(f) {
         dart.as(f, dart.functionType(dart.void, [DoubleLinkedQueueEntry$(E)]));
         let entry = this[_sentinel][_next];
-        while (!dart.notNull(core.identical(entry, this[_sentinel]))) {
+        while (!core.identical(entry, this[_sentinel])) {
           let nextEntry = entry[_next];
           f(entry);
           entry = nextEntry;
         }
       }
       get iterator() {
         return new (_DoubleLinkedQueueIterator$(E))(this[_sentinel]);
       }
       toString() {
         return IterableBase.iterableToFullString(this, '{', '}');
@@ skipping 35 matching lines @@
   let DoubleLinkedQueue = DoubleLinkedQueue$();
   const _nextEntry = Symbol('_nextEntry');
   const _DoubleLinkedQueueIterator$ = dart.generic(function(E) {
     class _DoubleLinkedQueueIterator extends core.Object {
       _DoubleLinkedQueueIterator(sentinel) {
         this[_sentinel] = sentinel;
         this[_nextEntry] = sentinel[_next];
         this[_current] = null;
       }
       moveNext() {
-        if (!dart.notNull(core.identical(this[_nextEntry], this[_sentinel]))) {
+        if (!core.identical(this[_nextEntry], this[_sentinel])) {
           this[_current] = this[_nextEntry][_element];
           this[_nextEntry] = this[_nextEntry][_next];
           return true;
         }
         this[_current] = null;
         this[_nextEntry] = this[_sentinel] = null;
         return false;
       }
       get current() {
         return this[_current];
@@ skipping 146 matching lines @@
       }
       [_filterWhere](test, removeMatching) {
         dart.as(test, dart.functionType(core.bool, [E]));
         let index = this[_head];
         let modificationCount = this[_modificationCount];
         let i = this[_head];
         while (i != this[_tail]) {
           let element = this[_table][dartx.get](i);
           let remove = core.identical(removeMatching, test(element));
           this[_checkModification](modificationCount);
-          if (dart.notNull(remove)) {
+          if (remove) {
             i = this[_remove](i);
             modificationCount = this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
           } else {
             i = dart.notNull(i) + 1 & dart.notNull(this[_table][dartx.length]) - 1;
           }
         }
       }
       removeWhere(test) {
         dart.as(test, dart.functionType(core.bool, [E]));
         this[_filterWhere](test, true);
@@ skipping 1339 matching lines @@
       _IdentityHashMap() {
         super._HashMap();
       }
       [_computeHashCode](key) {
         return core.identityHashCode(key) & 0x3ffffff;
       }
       [_findBucketIndex](bucket, key) {
         if (bucket == null) return -1;
         let length = bucket.length;
         for (let i = 0; i < length; i = i + 2) {
-          if (dart.notNull(core.identical(bucket[i], key))) return i;
+          if (core.identical(bucket[i], key)) return i;
         }
         return -1;
       }
     }
     return _IdentityHashMap;
   });
   let _IdentityHashMap = _IdentityHashMap$();
   const _equals = Symbol('_equals');
   const _hashCode = Symbol('_hashCode');
   const _CustomHashMap$ = dart.generic(function(K, V) {
@@ skipping 457 matching lines @@
         super._LinkedHashMap();
       }
       [_computeHashCode](key) {
         return core.identityHashCode(key) & 0x3ffffff;
       }
       [_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.notNull(core.identical(cell[_key], key))) return i;
+          if (core.identical(cell[_key], key)) return i;
         }
         return -1;
       }
     }
     return _LinkedIdentityHashMap;
   });
   let _LinkedIdentityHashMap = _LinkedIdentityHashMap$();
   const _LinkedCustomHashMap$ = dart.generic(function(K, V) {
     class _LinkedCustomHashMap extends _LinkedHashMap$(K, V) {
       _LinkedCustomHashMap(equals, hashCode, validKey) {
@@ skipping 406 matching lines @@
       [_newSet]() {
         return new (_IdentityHashSet$(E))();
       }
       [_computeHashCode](key) {
         return core.identityHashCode(key) & 0x3ffffff;
       }
       [_findBucketIndex](bucket, element) {
         if (bucket == null) return -1;
         let length = bucket.length;
         for (let i = 0; i < length; i++) {
-          if (dart.notNull(core.identical(bucket[i], element))) return i;
+          if (core.identical(bucket[i], element)) return i;
         }
         return -1;
       }
     }
     dart.setSignature(_IdentityHashSet, {
       methods: () => ({[_newSet]: [core.Set$(E), []]})
     });
     return _IdentityHashSet;
   });
   let _IdentityHashSet = _IdentityHashSet$();
@@ skipping 399 matching lines @@
         return new (_LinkedIdentityHashSet$(E))();
       }
       [_computeHashCode](key) {
         return core.identityHashCode(key) & 0x3ffffff;
       }
       [_findBucketIndex](bucket, element) {
         if (bucket == null) return -1;
         let length = bucket.length;
         for (let i = 0; i < length; i++) {
           let cell = dart.as(bucket[i], LinkedHashSetCell);
-          if (dart.notNull(core.identical(cell[_element], element))) return i;
+          if (core.identical(cell[_element], element)) return i;
         }
         return -1;
       }
     }
     dart.setSignature(_LinkedIdentityHashSet, {
       methods: () => ({[_newSet]: [core.Set$(E), []]})
     });
     return _LinkedIdentityHashSet;
   });
   let _LinkedIdentityHashSet = _LinkedIdentityHashSet$();
@@ skipping 164 matching lines @@
   exports.LinkedHashMapKeyIterable$ = LinkedHashMapKeyIterable$;
   exports.LinkedHashMapKeyIterable = LinkedHashMapKeyIterable;
   exports.LinkedHashMapKeyIterator$ = LinkedHashMapKeyIterator$;
   exports.LinkedHashMapKeyIterator = LinkedHashMapKeyIterator;
   exports.HashSetIterator$ = HashSetIterator$;
   exports.HashSetIterator = HashSetIterator;
   exports.LinkedHashSetCell = LinkedHashSetCell;
   exports.LinkedHashSetIterator$ = LinkedHashSetIterator$;
   exports.LinkedHashSetIterator = LinkedHashSetIterator;
 });