fixes #206, add checking for unary ops

lib/runtime/dart/collection.js

 var collection = dart.defineLibrary(collection, {});
 var _internal = dart.lazyImport(_internal);
 var core = dart.import(core);
 var _js_helper = dart.lazyImport(_js_helper);
 var math = dart.lazyImport(math);
 (function(exports, _internal, core, _js_helper, math) {
   'use strict';
   let _source = Symbol('_source');
   let UnmodifiableListView$ = dart.generic(function(E) {
     class UnmodifiableListView extends _internal.UnmodifiableListBase$(E) {
@@ skipping 125 matching lines @@
         let toRemove = this.toSet();
         for (let o of elements) {
           toRemove.remove(o);
         }
         this.removeAll(toRemove);
       }
       removeWhere(test) {
         dart.as(test, dart.functionType(core.bool, [E]));
         let toRemove = [];
         for (let element of this) {
-          if (test(element))
+          if (dart.notNull(test(element)))
             toRemove[dartx.add](element);
         }
         this.removeAll(toRemove);
       }
       retainWhere(test) {
         dart.as(test, dart.functionType(core.bool, [E]));
         let toRemove = [];
         for (let element of this) {
           if (!dart.notNull(test(element)))
             toRemove[dartx.add](element);
@@ skipping 17 matching lines @@
         let result = this.toSet();
         for (let element of this) {
           if (!dart.notNull(other.contains(element)))
             result.remove(element);
         }
         return result;
       }
       difference(other) {
         let result = this.toSet();
         for (let element of this) {
-          if (other.contains(element))
+          if (dart.notNull(other.contains(element)))
             result.remove(element);
         }
         return result;
       }
       toList(opts) {
         let growable = opts && 'growable' in opts ? opts.growable : true;
-        let result = growable ? (() => {
+        let result = dart.notNull(growable) ? (() => {
           let _ = core.List$(E).new();
           _.length = this.length;
           return _;
         })() : core.List$(E).new(this.length);
         let i = 0;
         for (let element of this)
           result[dartx.set]((() => {
             let x = i;
             i = dart.notNull(x) + 1;
             return x;
@@ skipping 29 matching lines @@
         for (let element of this)
           f(element);
       }
       reduce(combine) {
         dart.as(combine, dart.functionType(E, [E, E]));
         let iterator = this.iterator;
         if (!dart.notNull(iterator.moveNext())) {
           throw _internal.IterableElementError.noElement();
         }
         let value = iterator.current;
-        while (iterator.moveNext()) {
+        while (dart.notNull(iterator.moveNext())) {
           value = combine(value, iterator.current);
         }
         return value;
       }
       fold(initialValue, combine) {
         dart.as(combine, dart.functionType(core.Object, [dart.bottom, E]));
         let value = initialValue;
         for (let element of this)
           value = dart.dcall(combine, value, element);
         return value;
       }
       every(f) {
         dart.as(f, dart.functionType(core.bool, [E]));
         for (let element of this) {
           if (!dart.notNull(f(element)))
             return false;
         }
         return true;
       }
       join(separator) {
         if (separator === void 0)
           separator = "";
         let iterator = this.iterator;
         if (!dart.notNull(iterator.moveNext()))
           return "";
         let buffer = new core.StringBuffer();
         if (separator == null || separator == "") {
           do {
             buffer.write(`${iterator.current}`);
-          } while (iterator.moveNext());
+          } while (dart.notNull(iterator.moveNext()));
         } else {
           buffer.write(`${iterator.current}`);
-          while (iterator.moveNext()) {
+          while (dart.notNull(iterator.moveNext())) {
             buffer.write(separator);
             buffer.write(`${iterator.current}`);
           }
         }
         return dart.toString(buffer);
       }
       any(test) {
         dart.as(test, dart.functionType(core.bool, [E]));
         for (let element of this) {
-          if (test(element))
+          if (dart.notNull(test(element)))
             return true;
         }
         return false;
       }
       take(n) {
         return _internal.TakeIterable$(E).new(this, n);
       }
       takeWhile(test) {
         dart.as(test, dart.functionType(core.bool, [E]));
         return new (_internal.TakeWhileIterable$(E))(this, test);
@@ skipping 13 matching lines @@
         return it.current;
       }
       get last() {
         let it = this.iterator;
         if (!dart.notNull(it.moveNext())) {
           throw _internal.IterableElementError.noElement();
         }
         let result = null;
         do {
           result = it.current;
-        } while (it.moveNext());
+        } while (dart.notNull(it.moveNext()));
         return result;
       }
       firstWhere(test, opts) {
         dart.as(test, dart.functionType(core.bool, [E]));
         let orElse = opts && 'orElse' in opts ? opts.orElse : null;
         dart.as(orElse, dart.functionType(E, []));
         for (let element of this) {
-          if (test(element))
+          if (dart.notNull(test(element)))
             return element;
         }
         if (orElse != null)
           return orElse();
         throw _internal.IterableElementError.noElement();
       }
       lastWhere(test, opts) {
         dart.as(test, dart.functionType(core.bool, [E]));
         let orElse = opts && 'orElse' in opts ? opts.orElse : null;
         dart.as(orElse, dart.functionType(E, []));
         let result = null;
         let foundMatching = false;
         for (let element of this) {
-          if (test(element)) {
+          if (dart.notNull(test(element))) {
             result = element;
             foundMatching = true;
           }
         }
-        if (foundMatching)
+        if (dart.notNull(foundMatching))
           return result;
         if (orElse != null)
           return orElse();
         throw _internal.IterableElementError.noElement();
       }
       singleWhere(test) {
         dart.as(test, dart.functionType(core.bool, [E]));
         let result = null;
         let foundMatching = false;
         for (let element of this) {
-          if (test(element)) {
-            if (foundMatching) {
+          if (dart.notNull(test(element))) {
+            if (dart.notNull(foundMatching)) {
               throw _internal.IterableElementError.tooMany();
             }
             result = element;
             foundMatching = true;
           }
         }
-        if (foundMatching)
+        if (dart.notNull(foundMatching))
           return result;
         throw _internal.IterableElementError.noElement();
       }
       elementAt(index) {
         if (!(typeof index == 'number'))
           throw new core.ArgumentError.notNull("index");
         core.RangeError.checkNotNegative(index, "index");
         let elementIndex = 0;
         for (let element of this) {
           if (index == elementIndex)
@@ skipping 84 matching lines @@
         let result = this[_newSet]();
         for (let element of this) {
           if (!dart.notNull(other.contains(element)))
             result.add(element);
         }
         return result;
       }
       intersection(other) {
         let result = this[_newSet]();
         for (let element of this) {
-          if (other.contains(element))
+          if (dart.notNull(other.contains(element)))
             result.add(element);
         }
         return result;
       }
       toSet() {
         return (() => {
           let _ = this[_newSet]();
           _.addAll(this);
           return _;
         })();
@@ skipping 89 matching lines @@
         for (let element of this)
           f(element);
       }
       reduce(combine) {
         dart.as(combine, dart.functionType(E, [E, E]));
         let iterator = this.iterator;
         if (!dart.notNull(iterator.moveNext())) {
           throw _internal.IterableElementError.noElement();
         }
         let value = iterator.current;
-        while (iterator.moveNext()) {
+        while (dart.notNull(iterator.moveNext())) {
           value = combine(value, iterator.current);
         }
         return value;
       }
       fold(initialValue, combine) {
         dart.as(combine, dart.functionType(core.Object, [dart.bottom, E]));
         let value = initialValue;
         for (let element of this)
           value = dart.dcall(combine, value, element);
         return value;
       }
       every(f) {
         dart.as(f, dart.functionType(core.bool, [E]));
         for (let element of this) {
           if (!dart.notNull(f(element)))
             return false;
         }
         return true;
       }
       join(separator) {
         if (separator === void 0)
           separator = "";
         let iterator = this.iterator;
         if (!dart.notNull(iterator.moveNext()))
           return "";
         let buffer = new core.StringBuffer();
         if (separator == null || separator == "") {
           do {
             buffer.write(`${iterator.current}`);
-          } while (iterator.moveNext());
+          } while (dart.notNull(iterator.moveNext()));
         } else {
           buffer.write(`${iterator.current}`);
-          while (iterator.moveNext()) {
+          while (dart.notNull(iterator.moveNext())) {
             buffer.write(separator);
             buffer.write(`${iterator.current}`);
           }
         }
         return dart.toString(buffer);
       }
       any(f) {
         dart.as(f, dart.functionType(core.bool, [E]));
         for (let element of this) {
-          if (f(element))
+          if (dart.notNull(f(element)))
             return true;
         }
         return false;
       }
       toList(opts) {
         let growable = opts && 'growable' in opts ? opts.growable : true;
         return core.List$(E).from(this, {growable: growable});
       }
       toSet() {
         return core.Set$(E).from(this);
       }
       get length() {
         dart.assert(!dart.is(this, _internal.EfficientLength));
         let count = 0;
         let it = this[dartx.iterator];
-        while (it.moveNext()) {
+        while (dart.notNull(it.moveNext())) {
           count = dart.notNull(count) + 1;
         }
         return count;
       }
       get isEmpty() {
         return !dart.notNull(this[dartx.iterator].moveNext());
       }
       get isNotEmpty() {
         return !dart.notNull(this.isEmpty);
       }
@@ skipping 19 matching lines @@
         return it.current;
       }
       get last() {
         let it = this[dartx.iterator];
         if (!dart.notNull(it.moveNext())) {
           throw _internal.IterableElementError.noElement();
         }
         let result = null;
         do {
           result = it.current;
-        } while (it.moveNext());
+        } while (dart.notNull(it.moveNext()));
         return result;
       }
       get single() {
         let it = this[dartx.iterator];
         if (!dart.notNull(it.moveNext()))
           throw _internal.IterableElementError.noElement();
         let result = it.current;
-        if (it.moveNext())
+        if (dart.notNull(it.moveNext()))
           throw _internal.IterableElementError.tooMany();
         return result;
       }
       firstWhere(test, opts) {
         dart.as(test, dart.functionType(core.bool, [E]));
         let orElse = opts && 'orElse' in opts ? opts.orElse : null;
         dart.as(orElse, dart.functionType(E, []));
         for (let element of this) {
-          if (test(element))
+          if (dart.notNull(test(element)))
             return element;
         }
         if (orElse != null)
           return orElse();
         throw _internal.IterableElementError.noElement();
       }
       lastWhere(test, opts) {
         dart.as(test, dart.functionType(core.bool, [E]));
         let orElse = opts && 'orElse' in opts ? opts.orElse : null;
         dart.as(orElse, dart.functionType(E, []));
         let result = null;
         let foundMatching = false;
         for (let element of this) {
-          if (test(element)) {
+          if (dart.notNull(test(element))) {
             result = element;
             foundMatching = true;
           }
         }
-        if (foundMatching)
+        if (dart.notNull(foundMatching))
           return result;
         if (orElse != null)
           return orElse();
         throw _internal.IterableElementError.noElement();
       }
       singleWhere(test) {
         dart.as(test, dart.functionType(core.bool, [E]));
         let result = null;
         let foundMatching = false;
         for (let element of this) {
-          if (test(element)) {
-            if (foundMatching) {
+          if (dart.notNull(test(element))) {
+            if (dart.notNull(foundMatching)) {
               throw _internal.IterableElementError.tooMany();
             }
             result = element;
             foundMatching = true;
           }
         }
-        if (foundMatching)
+        if (dart.notNull(foundMatching))
           return result;
         throw _internal.IterableElementError.noElement();
       }
       elementAt(index) {
         if (!(typeof index == 'number'))
           throw new core.ArgumentError.notNull("index");
         core.RangeError.checkNotNegative(index, "index");
         let elementIndex = 0;
         for (let element of this) {
           if (index == elementIndex)
@@ skipping 93 matching lines @@
         for (let element of this)
           f(element);
       }
       reduce(combine) {
         dart.as(combine, dart.functionType(E, [E, E]));
         let iterator = this.iterator;
         if (!dart.notNull(iterator.moveNext())) {
           throw _internal.IterableElementError.noElement();
         }
         let value = iterator.current;
-        while (iterator.moveNext()) {
+        while (dart.notNull(iterator.moveNext())) {
           value = combine(value, iterator.current);
         }
         return value;
       }
       fold(initialValue, combine) {
         dart.as(combine, dart.functionType(core.Object, [dart.bottom, E]));
         let value = initialValue;
         for (let element of this)
           value = dart.dcall(combine, value, element);
         return value;
       }
       every(f) {
         dart.as(f, dart.functionType(core.bool, [E]));
         for (let element of this) {
           if (!dart.notNull(f(element)))
             return false;
         }
         return true;
       }
       join(separator) {
         if (separator === void 0)
           separator = "";
         let iterator = this.iterator;
         if (!dart.notNull(iterator.moveNext()))
           return "";
         let buffer = new core.StringBuffer();
         if (separator == null || separator == "") {
           do {
             buffer.write(`${iterator.current}`);
-          } while (iterator.moveNext());
+          } while (dart.notNull(iterator.moveNext()));
         } else {
           buffer.write(`${iterator.current}`);
-          while (iterator.moveNext()) {
+          while (dart.notNull(iterator.moveNext())) {
             buffer.write(separator);
             buffer.write(`${iterator.current}`);
           }
         }
         return dart.toString(buffer);
       }
       any(f) {
         dart.as(f, dart.functionType(core.bool, [E]));
         for (let element of this) {
-          if (f(element))
+          if (dart.notNull(f(element)))
             return true;
         }
         return false;
       }
       toList(opts) {
         let growable = opts && 'growable' in opts ? opts.growable : true;
         return core.List$(E).from(this, {growable: growable});
       }
       toSet() {
         return core.Set$(E).from(this);
       }
       get length() {
         dart.assert(!dart.is(this, _internal.EfficientLength));
         let count = 0;
         let it = this[dartx.iterator];
-        while (it.moveNext()) {
+        while (dart.notNull(it.moveNext())) {
           count = dart.notNull(count) + 1;
         }
         return count;
       }
       get isEmpty() {
         return !dart.notNull(this[dartx.iterator].moveNext());
       }
       get isNotEmpty() {
         return !dart.notNull(this.isEmpty);
       }
@@ skipping 19 matching lines @@
         return it.current;
       }
       get last() {
         let it = this[dartx.iterator];
         if (!dart.notNull(it.moveNext())) {
           throw _internal.IterableElementError.noElement();
         }
         let result = null;
         do {
           result = it.current;
-        } while (it.moveNext());
+        } while (dart.notNull(it.moveNext()));
         return result;
       }
       get single() {
         let it = this[dartx.iterator];
         if (!dart.notNull(it.moveNext()))
           throw _internal.IterableElementError.noElement();
         let result = it.current;
-        if (it.moveNext())
+        if (dart.notNull(it.moveNext()))
           throw _internal.IterableElementError.tooMany();
         return result;
       }
       firstWhere(test, opts) {
         dart.as(test, dart.functionType(core.bool, [E]));
         let orElse = opts && 'orElse' in opts ? opts.orElse : null;
         dart.as(orElse, dart.functionType(E, []));
         for (let element of this) {
-          if (test(element))
+          if (dart.notNull(test(element)))
             return element;
         }
         if (orElse != null)
           return orElse();
         throw _internal.IterableElementError.noElement();
       }
       lastWhere(test, opts) {
         dart.as(test, dart.functionType(core.bool, [E]));
         let orElse = opts && 'orElse' in opts ? opts.orElse : null;
         dart.as(orElse, dart.functionType(E, []));
         let result = null;
         let foundMatching = false;
         for (let element of this) {
-          if (test(element)) {
+          if (dart.notNull(test(element))) {
             result = element;
             foundMatching = true;
           }
         }
-        if (foundMatching)
+        if (dart.notNull(foundMatching))
           return result;
         if (orElse != null)
           return orElse();
         throw _internal.IterableElementError.noElement();
       }
       singleWhere(test) {
         dart.as(test, dart.functionType(core.bool, [E]));
         let result = null;
         let foundMatching = false;
         for (let element of this) {
-          if (test(element)) {
-            if (foundMatching) {
+          if (dart.notNull(test(element))) {
+            if (dart.notNull(foundMatching)) {
               throw _internal.IterableElementError.tooMany();
             }
             result = element;
             foundMatching = true;
           }
         }
-        if (foundMatching)
+        if (dart.notNull(foundMatching))
           return result;
         throw _internal.IterableElementError.noElement();
       }
       elementAt(index) {
         if (!(typeof index == 'number'))
           throw new core.ArgumentError.notNull("index");
         core.RangeError.checkNotNegative(index, "index");
         let elementIndex = 0;
         for (let element of this) {
           if (index == elementIndex)
             return element;
           elementIndex = dart.notNull(elementIndex) + 1;
         }
         throw core.RangeError.index(index, this, "index", null, elementIndex);
       }
       toString() {
         return IterableBase$().iterableToShortString(this, '(', ')');
       }
       static iterableToShortString(iterable, leftDelimiter, rightDelimiter) {
         if (leftDelimiter === void 0)
           leftDelimiter = '(';
         if (rightDelimiter === void 0)
           rightDelimiter = ')';
-        if (IterableBase$()._isToStringVisiting(iterable)) {
+        if (dart.notNull(IterableBase$()._isToStringVisiting(iterable))) {
           if (leftDelimiter == "(" && rightDelimiter == ")") {
             return "(...)";
           }
           return `${leftDelimiter}...${rightDelimiter}`;
         }
         let parts = [];
         IterableBase$()._toStringVisiting[dartx.add](iterable);
         try {
           IterableBase$()._iterablePartsToStrings(iterable, parts);
         } finally {
           dart.assert(core.identical(IterableBase$()._toStringVisiting[dartx.last], iterable));
           IterableBase$()._toStringVisiting[dartx.removeLast]();
         }
         return dart.toString((() => {
           let _ = new core.StringBuffer(leftDelimiter);
           _.writeAll(parts, ", ");
           _.write(rightDelimiter);
           return _;
         })());
       }
       static iterableToFullString(iterable, leftDelimiter, rightDelimiter) {
         if (leftDelimiter === void 0)
           leftDelimiter = '(';
         if (rightDelimiter === void 0)
           rightDelimiter = ')';
-        if (IterableBase$()._isToStringVisiting(iterable)) {
+        if (dart.notNull(IterableBase$()._isToStringVisiting(iterable))) {
           return `${leftDelimiter}...${rightDelimiter}`;
         }
         let buffer = new core.StringBuffer(leftDelimiter);
         IterableBase$()._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);
       }
       static _isToStringVisiting(o) {
         for (let i = 0; dart.notNull(i) < dart.notNull(IterableBase$()._toStringVisiting.length); i = dart.notNull(i) + 1) {
-          if (core.identical(o, IterableBase$()._toStringVisiting[dartx.get](i)))
+          if (dart.notNull(core.identical(o, IterableBase$()._toStringVisiting[dartx.get](i))))
             return true;
         }
         return false;
       }
       static _iterablePartsToStrings(iterable, parts) {
         let LENGTH_LIMIT = 80;
         let HEAD_COUNT = 3;
         let TAIL_COUNT = 2;
         let MAX_COUNT = 100;
         let OVERHEAD = 2;
@@ skipping 26 matching lines @@
               parts[dartx.add](`${penultimate}`);
               return;
             }
             ultimateString = `${penultimate}`;
             penultimateString = dart.as(parts[dartx.removeLast](), core.String);
             length = dart.notNull(length) + (dart.notNull(ultimateString.length) + dart.notNull(OVERHEAD));
           } else {
             ultimate = it.current;
             count = dart.notNull(count) + 1;
             dart.assert(dart.notNull(count) < dart.notNull(MAX_COUNT));
-            while (it.moveNext()) {
+            while (dart.notNull(it.moveNext())) {
               penultimate = ultimate;
               ultimate = it.current;
               count = dart.notNull(count) + 1;
               if (dart.notNull(count) > dart.notNull(MAX_COUNT)) {
                 while (dart.notNull(length) > dart.notNull(LENGTH_LIMIT) - dart.notNull(ELLIPSIS_SIZE) - dart.notNull(OVERHEAD) && dart.notNull(count) > dart.notNull(HEAD_COUNT)) {
                   length = dart.notNull(length) - dart.notNull(dart.as(dart.dsend(dart.dload(parts[dartx.removeLast](), 'length'), '+', OVERHEAD), core.int));
                   count = dart.notNull(count) - 1;
                 }
                 parts[dartx.add]("...");
                 return;
@@ skipping 111 matching lines @@
       }
       next() {
         if (!dart.notNull(this.hasNext))
           throw new core.StateError("No more elements");
         dart.assert(this[_state] == HasNextIterator$()._HAS_NEXT_AND_NEXT_IN_CURRENT);
         let result = dart.as(this[_iterator].current, E);
         this[_move]();
         return result;
       }
       [_move]() {
-        if (this[_iterator].moveNext()) {
+        if (dart.notNull(this[_iterator].moveNext())) {
           this[_state] = HasNextIterator$()._HAS_NEXT_AND_NEXT_IN_CURRENT;
         } else {
           this[_state] = HasNextIterator$()._NO_NEXT;
         }
       }
     }
     dart.setSignature(HasNextIterator, {
       constructors: () => ({HasNextIterator: [HasNextIterator$(E), [core.Iterator]]}),
       methods: () => ({
         next: [E, []],
@@ skipping 182 matching lines @@
         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;
         }
         this[_next] = this[_previous] = this;
         this[_length] = 0;
       }
       get first() {
-        if (core.identical(this[_next], this)) {
+        if (dart.notNull(core.identical(this[_next], this))) {
           throw new core.StateError('No such element');
         }
         return dart.as(this[_next], E);
       }
       get last() {
-        if (core.identical(this[_previous], this)) {
+        if (dart.notNull(core.identical(this[_previous], this))) {
           throw new core.StateError('No such element');
         }
         return dart.as(this[_previous], E);
       }
       get single() {
-        if (core.identical(this[_previous], this)) {
+        if (dart.notNull(core.identical(this[_previous], this))) {
           throw new core.StateError('No such element');
         }
         if (!dart.notNull(core.identical(this[_previous], this[_next]))) {
           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];
@@ skipping 65 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 (core.identical(this[_next], this[_list])) {
+        if (dart.notNull(core.identical(this[_next], this[_list]))) {
           this[_current] = null;
           return false;
         }
         if (this[_modificationCount] != this[_list][_modificationCount]) {
           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 (core.identical(this[_next], this[_list]))
+        if (dart.notNull(core.identical(this[_next], this[_list])))
           return null;
         let result = dart.as(this[_next], E);
         return result;
       }
       get previous() {
-        if (core.identical(this[_previous], this[_list]))
+        if (dart.notNull(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 74 matching lines @@
           if (length != this.length) {
             throw new core.ConcurrentModificationError(this);
           }
         }
         return true;
       }
       any(test) {
         dart.as(test, dart.functionType(core.bool, [E]));
         let length = this.length;
         for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
-          if (test(this.get(i)))
+          if (dart.notNull(test(this.get(i))))
             return true;
           if (length != this.length) {
             throw new core.ConcurrentModificationError(this);
           }
         }
         return false;
       }
       firstWhere(test, opts) {
         dart.as(test, dart.functionType(core.bool, [E]));
         let orElse = opts && 'orElse' in opts ? opts.orElse : null;
         dart.as(orElse, dart.functionType(E, []));
         let length = this.length;
         for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
           let element = this.get(i);
-          if (test(element))
+          if (dart.notNull(test(element)))
             return element;
           if (length != this.length) {
             throw new core.ConcurrentModificationError(this);
           }
         }
         if (orElse != null)
           return orElse();
         throw _internal.IterableElementError.noElement();
       }
       lastWhere(test, opts) {
         dart.as(test, dart.functionType(core.bool, [E]));
         let orElse = opts && 'orElse' in opts ? opts.orElse : null;
         dart.as(orElse, dart.functionType(E, []));
         let length = this.length;
         for (let i = dart.notNull(length) - 1; dart.notNull(i) >= 0; i = dart.notNull(i) - 1) {
           let element = this.get(i);
-          if (test(element))
+          if (dart.notNull(test(element)))
             return element;
           if (length != this.length) {
             throw new core.ConcurrentModificationError(this);
           }
         }
         if (orElse != null)
           return orElse();
         throw _internal.IterableElementError.noElement();
       }
       singleWhere(test) {
         dart.as(test, dart.functionType(core.bool, [E]));
         let length = this.length;
         let match = null;
         let matchFound = false;
         for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
           let element = this.get(i);
-          if (test(element)) {
-            if (matchFound) {
+          if (dart.notNull(test(element))) {
+            if (dart.notNull(matchFound)) {
               throw _internal.IterableElementError.tooMany();
             }
             matchFound = true;
             match = element;
           }
           if (length != this.length) {
             throw new core.ConcurrentModificationError(this);
           }
         }
-        if (matchFound)
+        if (dart.notNull(matchFound))
           return match;
         throw _internal.IterableElementError.noElement();
       }
       join(separator) {
         if (separator === void 0)
           separator = "";
         if (this.length == 0)
           return "";
         let buffer = new core.StringBuffer();
         buffer.writeAll(this, separator);
@@ skipping 47 matching lines @@
       take(count) {
         return new (_internal.SubListIterable$(E))(this, 0, count);
       }
       takeWhile(test) {
         dart.as(test, dart.functionType(core.bool, [E]));
         return new (_internal.TakeWhileIterable$(E))(this, test);
       }
       toList(opts) {
         let growable = opts && 'growable' in opts ? opts.growable : true;
         let result = null;
-        if (growable) {
+        if (dart.notNull(growable)) {
           result = core.List$(E).new();
           result.length = this.length;
         } else {
           result = core.List$(E).new(this.length);
         }
         for (let i = 0; dart.notNull(i) < dart.notNull(this.length); i = dart.notNull(i) + 1) {
           result[dartx.set](i, this.get(i));
         }
         return result;
       }
@@ skipping 403 matching lines @@
       containsValue(value) {
         for (let key of this.keys) {
           if (dart.equals(this.get(key), value))
             return true;
         }
         return false;
       }
       putIfAbsent(key, ifAbsent) {
         dart.as(key, K);
         dart.as(ifAbsent, dart.functionType(V, []));
-        if (this.keys[dartx.contains](key)) {
+        if (dart.notNull(this.keys[dartx.contains](key))) {
           return this.get(key);
         }
         return this.set(key, ifAbsent());
       }
       containsKey(key) {
         return this.keys[dartx.contains](key);
       }
       get length() {
         return this.keys.length;
       }
@@ skipping 116 matching lines @@
   let _MapBaseValueIterable = _MapBaseValueIterable$();
   let _keys = Symbol('_keys');
   let _MapBaseValueIterator$ = dart.generic(function(V) {
     class _MapBaseValueIterator extends core.Object {
       _MapBaseValueIterator(map) {
         this[_map] = map;
         this[_keys] = map.keys[dartx.iterator];
         this[_current] = null;
       }
       moveNext() {
-        if (this[_keys].moveNext()) {
+        if (dart.notNull(this[_keys].moveNext())) {
           this[_current] = dart.as(this[_map].get(this[_keys].current), V);
           return true;
         }
         this[_current] = null;
         return false;
       }
       get current() {
         return this[_current];
       }
     }
@@ skipping 96 matching lines @@
     }
     static containsKey(map, key) {
       for (let k of map.keys) {
         if (dart.equals(key, k)) {
           return true;
         }
       }
       return false;
     }
     static putIfAbsent(map, key, ifAbsent) {
-      if (map.containsKey(key)) {
+      if (dart.notNull(map.containsKey(key))) {
         return map.get(key);
       }
       let v = ifAbsent();
       map.set(key, v);
       return v;
     }
     static clear(map) {
       for (let k of map.keys[dartx.toList]()) {
         map.remove(k);
       }
     }
     static forEach(map, f) {
       for (let k of map.keys) {
         dart.dcall(f, k, map.get(k));
       }
     }
     static getValues(map) {
       return map.keys[dartx.map](dart.fn(key => map.get(key)));
     }
     static length(map) {
       return map.keys.length;
     }
     static isEmpty(map) {
       return map.keys[dartx.isEmpty];
     }
     static isNotEmpty(map) {
       return map.keys[dartx.isNotEmpty];
     }
     static mapToString(m) {
-      if (IterableBase._isToStringVisiting(m)) {
+      if (dart.notNull(IterableBase._isToStringVisiting(m))) {
         return '{...}';
       }
       let result = new core.StringBuffer();
       try {
         IterableBase._toStringVisiting[dartx.add](m);
         result.write('{');
         let first = true;
         m.forEach(dart.fn((k, v) => {
           if (!dart.notNull(first)) {
             result.write(', ');
@@ skipping 235 matching lines @@
           }
           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]))) {
           let next = entry[_next];
-          if (core.identical(removeMatching, test(entry.element))) {
+          if (dart.notNull(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 (core.identical(this[_sentinel][_next], this[_sentinel][_previous])) {
+        if (dart.notNull(core.identical(this[_sentinel][_next], this[_sentinel][_previous]))) {
           return this[_sentinel][_next].element;
         }
         throw _internal.IterableElementError.tooMany();
       }
       lastEntry() {
         return this[_sentinel].previousEntry();
       }
       firstEntry() {
         return this[_sentinel].nextEntry();
       }
@@ skipping 168 matching lines @@
           throw _internal.IterableElementError.tooMany();
         return this[_table][dartx.get](this[_head]);
       }
       elementAt(index) {
         core.RangeError.checkValidIndex(index, this);
         return this[_table][dartx.get](dart.notNull(this[_head]) + dart.notNull(index) & dart.notNull(this[_table].length) - 1);
       }
       toList(opts) {
         let growable = opts && 'growable' in opts ? opts.growable : true;
         let list = null;
-        if (growable) {
+        if (dart.notNull(growable)) {
           list = core.List$(E).new();
           list.length = this.length;
         } else {
           list = core.List$(E).new(this.length);
         }
         this[_writeToList](list);
         return list;
       }
       add(element) {
         dart.as(element, E);
@@ skipping 40 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 (remove) {
+          if (dart.notNull(remove)) {
             i = this[_remove](i);
             modificationCount = this[_modificationCount] = dart.notNull(this[_modificationCount]) + 1;
           } else {
             i = dart.notNull(i) + 1 & dart.notNull(this[_table].length) - 1;
           }
         }
       }
       removeWhere(test) {
         dart.as(test, dart.functionType(core.bool, [E]));
         this[_filterWhere](test, true);
@@ skipping 530 matching lines @@
       }
       get isEmpty() {
         return this[_root] == null;
       }
       get isNotEmpty() {
         return !dart.notNull(this.isEmpty);
       }
       forEach(f) {
         dart.as(f, dart.functionType(dart.void, [K, V]));
         let nodes = new (_SplayTreeNodeIterator$(K))(this);
-        while (nodes.moveNext()) {
+        while (dart.notNull(nodes.moveNext())) {
           let node = dart.as(nodes.current, _SplayTreeMapNode$(K, V));
           f(node.key, node.value);
         }
       }
       get length() {
         return this[_count];
       }
       clear() {
         this[_clear]();
       }
       containsKey(key) {
         return dart.notNull(this[_validKey](key)) && this[_splay](dart.as(key, K)) == 0;
       }
       containsValue(value) {
         let found = false;
         let initialSplayCount = this[_splayCount];
         let visit = node => {
           while (node != null) {
             if (dart.equals(node.value, value))
               return true;
             if (initialSplayCount != this[_splayCount]) {
               throw new core.ConcurrentModificationError(this);
             }
-            if (dart.notNull(node.right != null) && dart.notNull(visit(dart.as(node.right, _SplayTreeMapNode))))
+            if (node.right != null && dart.notNull(visit(dart.as(node.right, _SplayTreeMapNode))))
               return true;
             node = dart.as(node.left, _SplayTreeMapNode);
           }
           return false;
         };
         dart.fn(visit, core.bool, [_SplayTreeMapNode]);
         return visit(dart.as(this[_root], _SplayTreeMapNode));
       }
       get keys() {
         return new (_SplayTreeKeyIterable$(K))(this);
@@ skipping 130 matching lines @@
         } else {
           this[_tree][_splay](currentNode.key);
           this[_findLeftMostDescendent](this[_tree][_root].right);
           dart.assert(!dart.notNull(this[_workList][dartx.isEmpty]));
         }
       }
       moveNext() {
         if (this[_modificationCount] != this[_tree][_modificationCount]) {
           throw new core.ConcurrentModificationError(this[_tree]);
         }
-        if (this[_workList][dartx.isEmpty]) {
+        if (dart.notNull(this[_workList][dartx.isEmpty])) {
           this[_currentNode] = null;
           return false;
         }
-        if (this[_tree][_splayCount] != this[_splayCount] && dart.notNull(this[_currentNode] != null)) {
+        if (this[_tree][_splayCount] != this[_splayCount] && this[_currentNode] != null) {
           this[_rebuildWorkList](this[_currentNode]);
         }
         this[_currentNode] = this[_workList][dartx.removeLast]();
         this[_findLeftMostDescendent](this[_currentNode].right);
         return true;
       }
     }
     _SplayTreeIterator[dart.implements] = () => [core.Iterator$(T)];
     dart.defineNamedConstructor(_SplayTreeIterator, 'startAt');
     dart.setSignature(_SplayTreeIterator, {
@@ skipping 199 matching lines @@
         dart.as(elements, core.Iterable$(E));
         for (let element of elements) {
           let compare = this[_splay](element);
           if (compare != 0) {
             this[_addNewRoot](new (_SplayTreeNode$(E))(element), compare);
           }
         }
       }
       removeAll(elements) {
         for (let element of elements) {
-          if (this[_validKey](element))
+          if (dart.notNull(this[_validKey](element)))
             this[_remove](dart.as(element, E));
         }
       }
       retainAll(elements) {
         let retainSet = new (SplayTreeSet$(E))(this[_comparator], this[_validKey]);
         let modificationCount = this[_modificationCount];
         for (let object of elements) {
           if (modificationCount != this[_modificationCount]) {
             throw new core.ConcurrentModificationError(this);
           }
@@ skipping 10 matching lines @@
         if (!dart.notNull(this[_validKey](object)))
           return null;
         let comp = this[_splay](dart.as(object, E));
         if (comp != 0)
           return null;
         return this[_root].key;
       }
       intersection(other) {
         let result = new (SplayTreeSet$(E))(this[_comparator], this[_validKey]);
         for (let element of this) {
-          if (other.contains(element))
+          if (dart.notNull(other.contains(element)))
             result.add(element);
         }
         return result;
       }
       difference(other) {
         let result = new (SplayTreeSet$(E))(this[_comparator], this[_validKey]);
         for (let element of this) {
           if (!dart.notNull(other.contains(element)))
             result.add(element);
         }
@@ skipping 89 matching lines @@
       get isNotEmpty() {
         return !dart.notNull(this.isEmpty);
       }
       get keys() {
         return new (HashMapKeyIterable$(K))(this);
       }
       get values() {
         return _internal.MappedIterable$(K, V).new(this.keys, dart.fn(each => this.get(each), V, [core.Object]));
       }
       containsKey(key) {
-        if (_HashMap$()._isStringKey(key)) {
+        if (dart.notNull(_HashMap$()._isStringKey(key))) {
           let strings = this[_strings];
           return strings == null ? false : _HashMap$()._hasTableEntry(strings, key);
-        } else if (_HashMap$()._isNumericKey(key)) {
+        } else if (dart.notNull(_HashMap$()._isNumericKey(key))) {
           let nums = this[_nums];
           return nums == null ? false : _HashMap$()._hasTableEntry(nums, key);
         } else {
           return this[_containsKey](key);
         }
       }
       [_containsKey](key) {
         let rest = this[_rest];
         if (rest == null)
           return false;
         let bucket = this[_getBucket](rest, key);
         return dart.notNull(this[_findBucketIndex](bucket, key)) >= 0;
       }
       containsValue(value) {
         return this[_computeKeys]()[dartx.any](dart.fn(each => dart.equals(this.get(each), value), core.bool, [core.Object]));
       }
       addAll(other) {
         dart.as(other, core.Map$(K, V));
         other.forEach(dart.fn((key, value) => {
           dart.as(key, K);
           dart.as(value, V);
           this.set(key, value);
         }, core.Object, [K, V]));
       }
       get(key) {
-        if (_HashMap$()._isStringKey(key)) {
+        if (dart.notNull(_HashMap$()._isStringKey(key))) {
           let strings = this[_strings];
           return strings == null ? null : dart.as(_HashMap$()._getTableEntry(strings, key), V);
-        } else if (_HashMap$()._isNumericKey(key)) {
+        } else if (dart.notNull(_HashMap$()._isNumericKey(key))) {
           let nums = this[_nums];
           return nums == null ? null : dart.as(_HashMap$()._getTableEntry(nums, key), V);
         } else {
           return this[_get](key);
         }
       }
       [_get](key) {
         let rest = this[_rest];
         if (rest == null)
           return null;
         let bucket = this[_getBucket](rest, key);
         let index = this[_findBucketIndex](bucket, key);
         return dart.notNull(index) < 0 ? null : dart.as(bucket[dart.notNull(index) + 1], V);
       }
       set(key, value) {
         dart.as(key, K);
         dart.as(value, V);
-        if (_HashMap$()._isStringKey(key)) {
+        if (dart.notNull(_HashMap$()._isStringKey(key))) {
           let strings = this[_strings];
           if (strings == null)
             this[_strings] = strings = _HashMap$()._newHashTable();
           this[_addHashTableEntry](strings, key, value);
-        } else if (_HashMap$()._isNumericKey(key)) {
+        } else if (dart.notNull(_HashMap$()._isNumericKey(key))) {
           let nums = this[_nums];
           if (nums == null)
             this[_nums] = nums = _HashMap$()._newHashTable();
           this[_addHashTableEntry](nums, key, value);
         } else {
           this[_set](key, value);
         }
       }
       [_set](key, value) {
         dart.as(key, K);
@@ skipping 14 matching lines @@
           } else {
             bucket.push(key, value);
             this[_length] = dart.notNull(this[_length]) + 1;
             this[_keys] = null;
           }
         }
       }
       putIfAbsent(key, ifAbsent) {
         dart.as(key, K);
         dart.as(ifAbsent, dart.functionType(V, []));
-        if (this.containsKey(key))
+        if (dart.notNull(this.containsKey(key)))
           return this.get(key);
         let value = ifAbsent();
         this.set(key, value);
         return value;
       }
       remove(key) {
-        if (_HashMap$()._isStringKey(key)) {
+        if (dart.notNull(_HashMap$()._isStringKey(key))) {
           return this[_removeHashTableEntry](this[_strings], key);
-        } else if (_HashMap$()._isNumericKey(key)) {
+        } else if (dart.notNull(_HashMap$()._isNumericKey(key))) {
           return this[_removeHashTableEntry](this[_nums], key);
         } else {
           return this[_remove](key);
         }
       }
       [_remove](key) {
         let rest = this[_rest];
         if (rest == null)
           return null;
         let bucket = this[_getBucket](rest, key);
@@ skipping 67 matching lines @@
       [_addHashTableEntry](table, key, value) {
         dart.as(key, K);
         dart.as(value, V);
         if (!dart.notNull(_HashMap$()._hasTableEntry(table, key))) {
           this[_length] = dart.notNull(this[_length]) + 1;
           this[_keys] = null;
         }
         _HashMap$()._setTableEntry(table, key, value);
       }
       [_removeHashTableEntry](table, key) {
-        if (dart.notNull(table != null) && dart.notNull(_HashMap$()._hasTableEntry(table, key))) {
+        if (table != null && dart.notNull(_HashMap$()._hasTableEntry(table, key))) {
           let value = dart.as(_HashMap$()._getTableEntry(table, key), V);
           _HashMap$()._deleteTableEntry(table, key);
           this[_length] = dart.notNull(this[_length]) - 1;
           this[_keys] = null;
           return value;
         } else {
           return null;
         }
       }
       static _isStringKey(key) {
-        return typeof key == 'string' && dart.notNull(!dart.equals(key, '__proto__'));
+        return typeof key == 'string' && !dart.equals(key, '__proto__');
       }
       static _isNumericKey(key) {
         return dart.is(key, core.num) && (key & 0x3ffffff) === key;
       }
       [_computeHashCode](key) {
         return dart.hashCode(key) & 0x3ffffff;
       }
       static _hasTableEntry(table, key) {
         let entry = table[key];
         return entry != null;
@@ skipping 78 matching lines @@
         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; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 2) {
-          if (core.identical(bucket[i], key))
+          if (dart.notNull(core.identical(bucket[i], key)))
             return i;
         }
         return -1;
       }
     }
     return _IdentityHashMap;
   });
   let _IdentityHashMap = _IdentityHashMap$();
   let _equals = Symbol('_equals');
   let _hashCode = Symbol('_hashCode');
@@ skipping 26 matching lines @@
         return super[_remove](key);
       }
       [_computeHashCode](key) {
         return this[_hashCode](dart.as(key, K)) & 0x3ffffff;
       }
       [_findBucketIndex](bucket, key) {
         if (bucket == null)
           return -1;
         let length = bucket.length;
         for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 2) {
-          if (this[_equals](dart.as(bucket[i], K), dart.as(key, K)))
+          if (dart.notNull(this[_equals](dart.as(bucket[i], K), dart.as(key, K))))
             return i;
         }
         return -1;
       }
       toString() {
         return Maps.mapToString(this);
       }
     }
     dart.setSignature(_CustomHashMap, {
       constructors: () => ({_CustomHashMap: [_CustomHashMap$(K, V), [_Equality$(K), _Hasher$(K), dart.functionType(core.bool, [core.Object])]]}),
@@ skipping 111 matching lines @@
       get isNotEmpty() {
         return !dart.notNull(this.isEmpty);
       }
       get keys() {
         return new (LinkedHashMapKeyIterable$(K))(this);
       }
       get values() {
         return _internal.MappedIterable$(K, V).new(this.keys, dart.fn(each => this.get(each), V, [core.Object]));
       }
       containsKey(key) {
-        if (_LinkedHashMap$()._isStringKey(key)) {
+        if (dart.notNull(_LinkedHashMap$()._isStringKey(key))) {
           let strings = this[_strings];
           if (strings == null)
             return false;
           let cell = dart.as(_LinkedHashMap$()._getTableEntry(strings, key), LinkedHashMapCell);
           return cell != null;
-        } else if (_LinkedHashMap$()._isNumericKey(key)) {
+        } else if (dart.notNull(_LinkedHashMap$()._isNumericKey(key))) {
           let nums = this[_nums];
           if (nums == null)
             return false;
           let cell = dart.as(_LinkedHashMap$()._getTableEntry(nums, key), LinkedHashMapCell);
           return cell != null;
         } else {
           return this[_containsKey](key);
         }
       }
       [_containsKey](key) {
         let rest = this[_rest];
         if (rest == null)
           return false;
         let bucket = this[_getBucket](rest, key);
         return dart.notNull(this[_findBucketIndex](bucket, key)) >= 0;
       }
       containsValue(value) {
         return this.keys[dartx.any](dart.fn(each => dart.equals(this.get(each), value), core.bool, [core.Object]));
       }
       addAll(other) {
         dart.as(other, core.Map$(K, V));
         other.forEach(dart.fn((key, value) => {
           dart.as(key, K);
           dart.as(value, V);
           this.set(key, value);
         }, core.Object, [K, V]));
       }
       get(key) {
-        if (_LinkedHashMap$()._isStringKey(key)) {
+        if (dart.notNull(_LinkedHashMap$()._isStringKey(key))) {
           let strings = this[_strings];
           if (strings == null)
             return null;
           let cell = dart.as(_LinkedHashMap$()._getTableEntry(strings, key), LinkedHashMapCell);
           return cell == null ? null : dart.as(cell[_value], V);
-        } else if (_LinkedHashMap$()._isNumericKey(key)) {
+        } else if (dart.notNull(_LinkedHashMap$()._isNumericKey(key))) {
           let nums = this[_nums];
           if (nums == null)
             return null;
           let cell = dart.as(_LinkedHashMap$()._getTableEntry(nums, key), LinkedHashMapCell);
           return cell == null ? null : dart.as(cell[_value], V);
         } else {
           return this[_get](key);
         }
       }
       [_get](key) {
         let rest = this[_rest];
         if (rest == null)
           return null;
         let bucket = this[_getBucket](rest, key);
         let index = this[_findBucketIndex](bucket, key);
         if (dart.notNull(index) < 0)
           return null;
         let cell = dart.as(bucket[index], LinkedHashMapCell);
         return dart.as(cell[_value], V);
       }
       set(key, value) {
         dart.as(key, K);
         dart.as(value, V);
-        if (_LinkedHashMap$()._isStringKey(key)) {
+        if (dart.notNull(_LinkedHashMap$()._isStringKey(key))) {
           let strings = this[_strings];
           if (strings == null)
             this[_strings] = strings = _LinkedHashMap$()._newHashTable();
           this[_addHashTableEntry](strings, key, value);
-        } else if (_LinkedHashMap$()._isNumericKey(key)) {
+        } else if (dart.notNull(_LinkedHashMap$()._isNumericKey(key))) {
           let nums = this[_nums];
           if (nums == null)
             this[_nums] = nums = _LinkedHashMap$()._newHashTable();
           this[_addHashTableEntry](nums, key, value);
         } else {
           this[_set](key, value);
         }
       }
       [_set](key, value) {
         dart.as(key, K);
@@ skipping 13 matching lines @@
             cell[_value] = value;
           } else {
             let cell = this[_newLinkedCell](key, value);
             bucket.push(cell);
           }
         }
       }
       putIfAbsent(key, ifAbsent) {
         dart.as(key, K);
         dart.as(ifAbsent, dart.functionType(V, []));
-        if (this.containsKey(key))
+        if (dart.notNull(this.containsKey(key)))
           return this.get(key);
         let value = ifAbsent();
         this.set(key, value);
         return value;
       }
       remove(key) {
-        if (_LinkedHashMap$()._isStringKey(key)) {
+        if (dart.notNull(_LinkedHashMap$()._isStringKey(key))) {
           return this[_removeHashTableEntry](this[_strings], key);
-        } else if (_LinkedHashMap$()._isNumericKey(key)) {
+        } else if (dart.notNull(_LinkedHashMap$()._isNumericKey(key))) {
           return this[_removeHashTableEntry](this[_nums], key);
         } else {
           return this[_remove](key);
         }
       }
       [_remove](key) {
         let rest = this[_rest];
         if (rest == null)
           return null;
         let bucket = this[_getBucket](rest, key);
@@ skipping 73 matching lines @@
         if (next == null) {
           dart.assert(dart.equals(cell, this[_last]));
           this[_last] = previous;
         } else {
           next[_previous] = previous;
         }
         this[_length] = dart.notNull(this[_length]) - 1;
         this[_modified]();
       }
       static _isStringKey(key) {
-        return typeof key == 'string' && dart.notNull(!dart.equals(key, '__proto__'));
+        return typeof key == 'string' && !dart.equals(key, '__proto__');
       }
       static _isNumericKey(key) {
         return dart.is(key, core.num) && (key & 0x3ffffff) === key;
       }
       [_computeHashCode](key) {
         return dart.hashCode(key) & 0x3ffffff;
       }
       static _getTableEntry(table, key) {
         return table[key];
       }
@@ skipping 76 matching lines @@
       }
       [_computeHashCode](key) {
         return core.identityHashCode(key) & 0x3ffffff;
       }
       [_findBucketIndex](bucket, key) {
         if (bucket == null)
           return -1;
         let length = bucket.length;
         for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
           let cell = dart.as(bucket[i], LinkedHashMapCell);
-          if (core.identical(cell[_key], key))
+          if (dart.notNull(core.identical(cell[_key], key)))
             return i;
         }
         return -1;
       }
     }
     return _LinkedIdentityHashMap;
   });
   let _LinkedIdentityHashMap = _LinkedIdentityHashMap$();
   let _LinkedCustomHashMap$ = dart.generic(function(K, V) {
     class _LinkedCustomHashMap extends _LinkedHashMap$(K, V) {
@@ skipping 25 matching lines @@
       }
       [_computeHashCode](key) {
         return this[_hashCode](dart.as(key, K)) & 0x3ffffff;
       }
       [_findBucketIndex](bucket, key) {
         if (bucket == null)
           return -1;
         let length = bucket.length;
         for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
           let cell = dart.as(bucket[i], LinkedHashMapCell);
-          if (this[_equals](dart.as(cell[_key], K), dart.as(key, K)))
+          if (dart.notNull(this[_equals](dart.as(cell[_key], K), dart.as(key, K))))
             return i;
         }
         return -1;
       }
     }
     dart.setSignature(_LinkedCustomHashMap, {
       constructors: () => ({_LinkedCustomHashMap: [_LinkedCustomHashMap$(K, V), [_Equality$(K), _Hasher$(K), dart.functionType(core.bool, [core.Object])]]}),
       methods: () => ({
         get: [V, [core.Object]],
         set: [dart.void, [K, V]],
@@ skipping 116 matching lines @@
       get length() {
         return this[_length];
       }
       get isEmpty() {
         return this[_length] == 0;
       }
       get isNotEmpty() {
         return !dart.notNull(this.isEmpty);
       }
       contains(object) {
-        if (_HashSet$()._isStringElement(object)) {
+        if (dart.notNull(_HashSet$()._isStringElement(object))) {
           let strings = this[_strings];
           return strings == null ? false : _HashSet$()._hasTableEntry(strings, object);
-        } else if (_HashSet$()._isNumericElement(object)) {
+        } else if (dart.notNull(_HashSet$()._isNumericElement(object))) {
           let nums = this[_nums];
           return nums == null ? false : _HashSet$()._hasTableEntry(nums, object);
         } else {
           return this[_contains](object);
         }
       }
       [_contains](object) {
         let rest = this[_rest];
         if (rest == null)
           return false;
         let bucket = this[_getBucket](rest, object);
         return dart.notNull(this[_findBucketIndex](bucket, object)) >= 0;
       }
       lookup(object) {
         if (dart.notNull(_HashSet$()._isStringElement(object)) || dart.notNull(_HashSet$()._isNumericElement(object))) {
-          return dart.as(this.contains(object) ? object : null, E);
+          return dart.as(dart.notNull(this.contains(object)) ? object : null, E);
         }
         return this[_lookup](object);
       }
       [_lookup](object) {
         let rest = this[_rest];
         if (rest == null)
           return null;
         let bucket = this[_getBucket](rest, object);
         let index = this[_findBucketIndex](bucket, object);
         if (dart.notNull(index) < 0)
           return null;
         return dart.as(bucket[dartx.get](index), E);
       }
       add(element) {
         dart.as(element, E);
-        if (_HashSet$()._isStringElement(element)) {
+        if (dart.notNull(_HashSet$()._isStringElement(element))) {
           let strings = this[_strings];
           if (strings == null)
             this[_strings] = strings = _HashSet$()._newHashTable();
           return this[_addHashTableEntry](strings, element);
-        } else if (_HashSet$()._isNumericElement(element)) {
+        } else if (dart.notNull(_HashSet$()._isNumericElement(element))) {
           let nums = this[_nums];
           if (nums == null)
             this[_nums] = nums = _HashSet$()._newHashTable();
           return this[_addHashTableEntry](nums, element);
         } else {
           return this[_add](element);
         }
       }
       [_add](element) {
         dart.as(element, E);
@@ skipping 14 matching lines @@
         this[_elements] = null;
         return true;
       }
       addAll(objects) {
         dart.as(objects, core.Iterable$(E));
         for (let each of objects) {
           this.add(each);
         }
       }
       remove(object) {
-        if (_HashSet$()._isStringElement(object)) {
+        if (dart.notNull(_HashSet$()._isStringElement(object))) {
           return this[_removeHashTableEntry](this[_strings], object);
-        } else if (_HashSet$()._isNumericElement(object)) {
+        } else if (dart.notNull(_HashSet$()._isNumericElement(object))) {
           return this[_removeHashTableEntry](this[_nums], object);
         } else {
           return this[_remove](object);
         }
       }
       [_remove](object) {
         let rest = this[_rest];
         if (rest == null)
           return false;
         let bucket = this[_getBucket](rest, object);
@@ skipping 48 matching lines @@
               result[index] = bucket[i];
               index = dart.notNull(index) + 1;
             }
           }
         }
         dart.assert(index == this[_length]);
         return this[_elements] = result;
       }
       [_addHashTableEntry](table, element) {
         dart.as(element, E);
-        if (_HashSet$()._hasTableEntry(table, element))
+        if (dart.notNull(_HashSet$()._hasTableEntry(table, element)))
           return false;
         _HashSet$()._setTableEntry(table, element, 0);
         this[_length] = dart.notNull(this[_length]) + 1;
         this[_elements] = null;
         return true;
       }
       [_removeHashTableEntry](table, element) {
-        if (dart.notNull(table != null) && dart.notNull(_HashSet$()._hasTableEntry(table, element))) {
+        if (table != null && dart.notNull(_HashSet$()._hasTableEntry(table, element))) {
           _HashSet$()._deleteTableEntry(table, element);
           this[_length] = dart.notNull(this[_length]) - 1;
           this[_elements] = null;
           return true;
         } else {
           return false;
         }
       }
       static _isStringElement(element) {
-        return typeof element == 'string' && dart.notNull(!dart.equals(element, '__proto__'));
+        return typeof element == 'string' && !dart.equals(element, '__proto__');
       }
       static _isNumericElement(element) {
         return dart.is(element, core.num) && (element & 0x3ffffff) === element;
       }
       [_computeHashCode](element) {
         return dart.hashCode(element) & 0x3ffffff;
       }
       static _hasTableEntry(table, key) {
         let entry = table[key];
         return entry != null;
@@ skipping 77 matching lines @@
         return new (_IdentityHashSet$(E))();
       }
       [_computeHashCode](key) {
         return core.identityHashCode(key) & 0x3ffffff;
       }
       [_findBucketIndex](bucket, element) {
         if (bucket == null)
           return -1;
         let length = bucket.length;
         for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
-          if (core.identical(bucket[i], element))
+          if (dart.notNull(core.identical(bucket[i], element)))
             return i;
         }
         return -1;
       }
     }
     dart.setSignature(_IdentityHashSet, {
       methods: () => ({[_newSet]: [core.Set$(E), []]})
     });
     return _IdentityHashSet;
   });
   let _IdentityHashSet = _IdentityHashSet$();
   let _equality = Symbol('_equality');
   let _hasher = Symbol('_hasher');
   let _CustomHashSet$ = dart.generic(function(E) {
     class _CustomHashSet extends _HashSet$(E) {
       _CustomHashSet(equality, hasher, validKey) {
         this[_equality] = equality;
         this[_hasher] = hasher;
         this[_validKey] = validKey != null ? validKey : dart.fn(x => dart.is(x, E), core.bool, [core.Object]);
         super._HashSet();
       }
       [_newSet]() {
         return new (_CustomHashSet$(E))(this[_equality], this[_hasher], this[_validKey]);
       }
       [_findBucketIndex](bucket, element) {
         if (bucket == null)
           return -1;
         let length = bucket.length;
         for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
-          if (this[_equality](dart.as(bucket[i], E), dart.as(element, E)))
+          if (dart.notNull(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;
       }
       add(object) {
         dart.as(object, E);
         return super[_add](object);
@@ skipping 83 matching lines @@
       get length() {
         return this[_length];
       }
       get isEmpty() {
         return this[_length] == 0;
       }
       get isNotEmpty() {
         return !dart.notNull(this.isEmpty);
       }
       contains(object) {
-        if (_LinkedHashSet$()._isStringElement(object)) {
+        if (dart.notNull(_LinkedHashSet$()._isStringElement(object))) {
           let strings = this[_strings];
           if (strings == null)
             return false;
           let cell = dart.as(_LinkedHashSet$()._getTableEntry(strings, object), LinkedHashSetCell);
           return cell != null;
-        } else if (_LinkedHashSet$()._isNumericElement(object)) {
+        } else if (dart.notNull(_LinkedHashSet$()._isNumericElement(object))) {
           let nums = this[_nums];
           if (nums == null)
             return false;
           let cell = dart.as(_LinkedHashSet$()._getTableEntry(nums, object), LinkedHashSetCell);
           return cell != null;
         } else {
           return this[_contains](object);
         }
       }
       [_contains](object) {
         let rest = this[_rest];
         if (rest == null)
           return false;
         let bucket = this[_getBucket](rest, object);
         return dart.notNull(this[_findBucketIndex](bucket, object)) >= 0;
       }
       lookup(object) {
         if (dart.notNull(_LinkedHashSet$()._isStringElement(object)) || dart.notNull(_LinkedHashSet$()._isNumericElement(object))) {
-          return dart.as(this.contains(object) ? object : null, E);
+          return dart.as(dart.notNull(this.contains(object)) ? object : null, E);
         } else {
           return this[_lookup](object);
         }
       }
       [_lookup](object) {
         let rest = this[_rest];
         if (rest == null)
           return null;
         let bucket = this[_getBucket](rest, object);
         let index = this[_findBucketIndex](bucket, object);
@@ skipping 18 matching lines @@
           throw new core.StateError("No elements");
         return dart.as(this[_first][_element], E);
       }
       get last() {
         if (this[_last] == null)
           throw new core.StateError("No elements");
         return dart.as(this[_last][_element], E);
       }
       add(element) {
         dart.as(element, E);
-        if (_LinkedHashSet$()._isStringElement(element)) {
+        if (dart.notNull(_LinkedHashSet$()._isStringElement(element))) {
           let strings = this[_strings];
           if (strings == null)
             this[_strings] = strings = _LinkedHashSet$()._newHashTable();
           return this[_addHashTableEntry](strings, element);
-        } else if (_LinkedHashSet$()._isNumericElement(element)) {
+        } else if (dart.notNull(_LinkedHashSet$()._isNumericElement(element))) {
           let nums = this[_nums];
           if (nums == null)
             this[_nums] = nums = _LinkedHashSet$()._newHashTable();
           return this[_addHashTableEntry](nums, element);
         } else {
           return this[_add](element);
         }
       }
       [_add](element) {
         dart.as(element, E);
         let rest = this[_rest];
         if (rest == null)
           this[_rest] = rest = _LinkedHashSet$()._newHashTable();
         let hash = this[_computeHashCode](element);
         let bucket = rest[hash];
         if (bucket == null) {
           let cell = this[_newLinkedCell](element);
           _LinkedHashSet$()._setTableEntry(rest, hash, [cell]);
         } else {
           let index = this[_findBucketIndex](bucket, element);
           if (dart.notNull(index) >= 0)
             return false;
           let cell = this[_newLinkedCell](element);
           bucket.push(cell);
         }
         return true;
       }
       remove(object) {
-        if (_LinkedHashSet$()._isStringElement(object)) {
+        if (dart.notNull(_LinkedHashSet$()._isStringElement(object))) {
           return this[_removeHashTableEntry](this[_strings], object);
-        } else if (_LinkedHashSet$()._isNumericElement(object)) {
+        } else if (dart.notNull(_LinkedHashSet$()._isNumericElement(object))) {
           return this[_removeHashTableEntry](this[_nums], object);
         } else {
           return this[_remove](object);
         }
       }
       [_remove](object) {
         let rest = this[_rest];
         if (rest == null)
           return false;
         let bucket = this[_getBucket](rest, object);
@@ skipping 16 matching lines @@
         dart.as(test, dart.functionType(core.bool, [E]));
         let cell = this[_first];
         while (cell != null) {
           let element = dart.as(cell[_element], E);
           let next = cell[_next];
           let modifications = this[_modifications];
           let shouldRemove = removeMatching == test(element);
           if (modifications != this[_modifications]) {
             throw new core.ConcurrentModificationError(this);
           }
-          if (shouldRemove)
+          if (dart.notNull(shouldRemove))
             this.remove(element);
           cell = next;
         }
       }
       clear() {
         if (dart.notNull(this[_length]) > 0) {
           this[_strings] = this[_nums] = this[_rest] = this[_first] = this[_last] = null;
           this[_length] = 0;
           this[_modified]();
         }
@@ skipping 45 matching lines @@
         if (next == null) {
           dart.assert(dart.equals(cell, this[_last]));
           this[_last] = previous;
         } else {
           next[_previous] = previous;
         }
         this[_length] = dart.notNull(this[_length]) - 1;
         this[_modified]();
       }
       static _isStringElement(element) {
-        return typeof element == 'string' && dart.notNull(!dart.equals(element, '__proto__'));
+        return typeof element == 'string' && !dart.equals(element, '__proto__');
       }
       static _isNumericElement(element) {
         return dart.is(element, core.num) && (element & 0x3ffffff) === element;
       }
       [_computeHashCode](element) {
         return dart.hashCode(element) & 0x3ffffff;
       }
       static _getTableEntry(table, key) {
         return table[key];
       }
@@ skipping 87 matching lines @@
       }
       [_computeHashCode](key) {
         return core.identityHashCode(key) & 0x3ffffff;
       }
       [_findBucketIndex](bucket, element) {
         if (bucket == null)
           return -1;
         let length = bucket.length;
         for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
           let cell = dart.as(bucket[i], LinkedHashSetCell);
-          if (core.identical(cell[_element], element))
+          if (dart.notNull(core.identical(cell[_element], element)))
             return i;
         }
         return -1;
       }
     }
     dart.setSignature(_LinkedIdentityHashSet, {
       methods: () => ({[_newSet]: [core.Set$(E), []]})
     });
     return _LinkedIdentityHashSet;
   });
   let _LinkedIdentityHashSet = _LinkedIdentityHashSet$();
   let _LinkedCustomHashSet$ = dart.generic(function(E) {
     class _LinkedCustomHashSet extends _LinkedHashSet$(E) {
       _LinkedCustomHashSet(equality, hasher, validKey) {
         this[_equality] = equality;
         this[_hasher] = hasher;
         this[_validKey] = validKey != null ? validKey : dart.fn(x => dart.is(x, E), core.bool, [core.Object]);
         super._LinkedHashSet();
       }
       [_newSet]() {
         return new (_LinkedCustomHashSet$(E))(this[_equality], this[_hasher], this[_validKey]);
       }
       [_findBucketIndex](bucket, element) {
         if (bucket == null)
           return -1;
         let length = bucket.length;
         for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
           let cell = dart.as(bucket[i], LinkedHashSetCell);
-          if (this[_equality](dart.as(cell[_element], E), dart.as(element, E)))
+          if (dart.notNull(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;
       }
       add(element) {
         dart.as(element, E);
         return super[_add](element);
@@ skipping 15 matching lines @@
       }
       containsAll(elements) {
         for (let element of elements) {
           if (!dart.notNull(this[_validKey](element)) || !dart.notNull(this.contains(element)))
             return false;
         }
         return true;
       }
       removeAll(elements) {
         for (let element of elements) {
-          if (this[_validKey](element)) {
+          if (dart.notNull(this[_validKey](element))) {
             super[_remove](element);
           }
         }
       }
     }
     dart.setSignature(_LinkedCustomHashSet, {
       constructors: () => ({_LinkedCustomHashSet: [_LinkedCustomHashSet$(E), [_Equality$(E), _Hasher$(E), dart.functionType(core.bool, [core.Object])]]}),
       methods: () => ({
         [_newSet]: [core.Set$(E), []],
         add: [core.bool, [E]],
@@ skipping 105 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;
 })(collection, _internal, core, _js_helper, math);