fixes #130, accept anything with `iterator` in for loops

lib/runtime/dart/collection.js

 var collection;
 (function(exports) {
   'use strict';
   let _source = Symbol('_source');
   let UnmodifiableListView$ = dart.generic(function(E) {
     class UnmodifiableListView extends _internal.UnmodifiableListBase$(E) {
       UnmodifiableListView(source) {
         this[_source] = source;
       }
       get [core.$length]() {
@@ skipping 91 matching lines @@
   });
   let __CastType0 = __CastType0$();
   let __CastType2$ = dart.generic(function(K) {
     let __CastType2 = dart.typedef('__CastType2', () => dart.functionType(core.bool, [K, K]));
     return __CastType2;
   });
   let __CastType2 = __CastType2$();
   let _newSet = Symbol('_newSet');
   let SetMixin$ = dart.generic(function(E) {
     class SetMixin extends core.Object {
+      [Symbol.iterator]() {
+        return new dart.JsIterator(this[core.$iterator]);
+      }
       get [core.$isEmpty]() {
         return this[core.$length] == 0;
       }
       get [core.$isNotEmpty]() {
         return this[core.$length] != 0;
       }
       clear() {
         this.removeAll(this[core.$toList]());
       }
       addAll(elements) {
@@ skipping 325 matching lines @@
       }
       identity() {
         return new (_IdentityHashSet$(E))();
       }
       from(elements) {
         let result = new (HashSet$(E))();
         for (let e of dart.as(elements, core.Iterable$(E)))
           result.add(e);
         return result;
       }
+      [Symbol.iterator]() {
+        return new dart.JsIterator(this[core.$iterator]);
+      }
     }
     HashSet[dart.implements] = () => [core.Set$(E)];
     dart.defineNamedConstructor(HashSet, 'identity');
     dart.defineNamedConstructor(HashSet, 'from');
     return HashSet;
   });
   let HashSet = HashSet$();
   let __CastType5$ = dart.generic(function(E) {
     let __CastType5 = dart.typedef('__CastType5', () => dart.functionType(core.int, [E]));
     return __CastType5;
@@ skipping 203 matching lines @@
         for (let element of this) {
           if (index == elementIndex)
             return element;
           elementIndex = dart.notNull(elementIndex) + 1;
         }
         throw new core.RangeError.index(index, this, "index", null, elementIndex);
       }
       toString() {
         return IterableBase.iterableToShortString(this, '(', ')');
       }
+      [Symbol.iterator]() {
+        return new dart.JsIterator(this[core.$iterator]);
+      }
     }
     IterableMixin[dart.implements] = () => [core.Iterable$(E)];
     return IterableMixin;
   });
   let IterableMixin = IterableMixin$();
   let IterableBase$ = dart.generic(function(E) {
     class IterableBase extends core.Object {
       IterableBase() {
       }
       [core.$map](f) {
@@ skipping 323 matching lines @@
             elision = "...";
             length = dart.notNull(length) + (dart.notNull(ELLIPSIS_SIZE) + dart.notNull(OVERHEAD));
           }
         }
         if (elision != null) {
           parts[core.$add](elision);
         }
         parts[core.$add](penultimateString);
         parts[core.$add](ultimateString);
       }
+      [Symbol.iterator]() {
+        return new dart.JsIterator(this[core.$iterator]);
+      }
     }
     IterableBase[dart.implements] = () => [core.Iterable$(E)];
     dart.defineLazyProperties(IterableBase, {
       get _toStringVisiting() {
         return [];
       }
     });
     return IterableBase;
   });
   let IterableBase = IterableBase$();
@@ skipping 145 matching lines @@
       identity() {
         return new (_LinkedIdentityHashSet$(E))();
       }
       from(elements) {
         let result = new (LinkedHashSet$(E))();
         for (let element of elements) {
           result.add(element);
         }
         return result;
       }
+      [Symbol.iterator]() {
+        return new dart.JsIterator(this[core.$iterator]);
+      }
     }
     LinkedHashSet[dart.implements] = () => [HashSet$(E)];
     dart.defineNamedConstructor(LinkedHashSet, 'identity');
     dart.defineNamedConstructor(LinkedHashSet, 'from');
     return LinkedHashSet;
   });
   let LinkedHashSet = LinkedHashSet$();
   let __CastType15$ = dart.generic(function(E) {
     let __CastType15 = dart.typedef('__CastType15', () => dart.functionType(core.int, [E]));
     return __CastType15;
@@ skipping 191 matching lines @@
     }
     LinkedListEntry[dart.implements] = () => [_LinkedListLink];
     return LinkedListEntry;
   });
   let LinkedListEntry = LinkedListEntry$();
   let ListMixin$ = dart.generic(function(E) {
     class ListMixin extends core.Object {
       get [core.$iterator]() {
         return new (_internal.ListIterator$(E))(this);
       }
+      [Symbol.iterator]() {
+        return new dart.JsIterator(this[core.$iterator]);
+      }
       [core.$elementAt](index) {
         return this[core.$get](index);
       }
       [core.$forEach](action) {
         dart.as(action, dart.functionType(dart.void, [E]));
         let length = this[core.$length];
         for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
           action(this[core.$get](i));
           if (length != this[core.$length]) {
             throw new core.ConcurrentModificationError(this);
@@ skipping 796 matching lines @@
     }
   }
   let Queue$ = dart.generic(function(E) {
     class Queue extends core.Object {
       Queue() {
         return new (ListQueue$(E))();
       }
       from(elements) {
         return new ListQueue$(E).from(elements);
       }
+      [Symbol.iterator]() {
+        return new dart.JsIterator(this[core.$iterator]);
+      }
     }
     Queue[dart.implements] = () => [core.Iterable$(E), _internal.EfficientLength];
     dart.defineNamedConstructor(Queue, 'from');
     return Queue;
   });
   let Queue = Queue$();
   let _element = Symbol('_element');
   let _link = Symbol('_link');
   let _asNonSentinelEntry = Symbol('_asNonSentinelEntry');
   let DoubleLinkedQueueEntry$ = dart.generic(function(E) {
@@ skipping 2954 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 || (collection = {}));