Make IterableMixinWorkaround using classes return correctly typed Iterables.

runtime/lib/growable_array.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 class _GrowableList<T> implements List<T> {
 
   void insert(int index, T element) {
     if ((index < 0) || (index > length)) {
       throw new RangeError.range(index, 0, length);
     }
@@ skipping 59 matching lines @@
   void removeWhere(bool test(T element)) {
     IterableMixinWorkaround.removeWhereList(this, test);
   }
 
   void retainWhere(bool test(T element)) {
     IterableMixinWorkaround.removeWhereList(this,
                                             (T element) => !test(element));
   }
 
   Iterable<T> getRange(int start, int end) {
-    return IterableMixinWorkaround.getRangeList(this, start, end);
+    return new IterableMixinWorkaround<T>().getRangeList(this, start, end);
   }
 
   void setRange(int start, int end, Iterable<T> iterable, [int skipCount = 0]) {
     IterableMixinWorkaround.setRangeList(this, start, end, iterable, skipCount);
   }
 
   void removeRange(int start, int end) {
     Lists.indicesCheck(this, start, end);
     Lists.copy(this, end, this, start, this.length - end);
     this.length = this.length - (end - start);
@@ skipping 118 matching lines @@
   }
 
   void _grow(int new_length) {
     var new_data = new _List(new_length);
     for (int i = 0; i < length; i++) {
       new_data[i] = this[i];
     }
     _setData(new_data);
   }
 
-  // Collection interface.
+  // Iterable interface.
 
   bool contains(Object element) {
     return IterableMixinWorkaround.contains(this, element);
   }
 
   void forEach(f(T element)) {
     int initialLength = length;
     for (int i = 0; i < length; i++) {
       f(this[i]);
       if (length != initialLength) throw new ConcurrentModificationError(this);
@@ skipping 24 matching lines @@
 
   T reduce(T combine(T value, T element)) {
     return IterableMixinWorkaround.reduce(this, combine);
   }
 
   fold(initialValue, combine(previousValue, T element)) {
     return IterableMixinWorkaround.fold(this, initialValue, combine);
   }
 
   Iterable<T> where(bool f(T element)) {
-    return IterableMixinWorkaround.where(this, f);
+    return new IterableMixinWorkaround<T>().where(this, f);
   }
 
   Iterable expand(Iterable f(T element)) {
     return IterableMixinWorkaround.expand(this, f);
   }
 
   Iterable<T> take(int n) {
-    return IterableMixinWorkaround.takeList(this, n);
+    return new IterableMixinWorkaround<T>().takeList(this, n);
   }
 
   Iterable<T> takeWhile(bool test(T value)) {
-    return IterableMixinWorkaround.takeWhile(this, test);
+    return new IterableMixinWorkaround<T>().takeWhile(this, test);
   }
 
   Iterable<T> skip(int n) {
-    return IterableMixinWorkaround.skipList(this, n);
+    return new IterableMixinWorkaround<T>().skipList(this, n);
   }
 
   Iterable<T> skipWhile(bool test(T value)) {
-    return IterableMixinWorkaround.skipWhile(this, test);
+    return new IterableMixinWorkaround<T>().skipWhile(this, test);
   }
 
   bool every(bool f(T element)) {
     return IterableMixinWorkaround.every(this, f);
   }
 
   bool any(bool f(T element)) {
     return IterableMixinWorkaround.any(this, f);
   }
 
@@ skipping 16 matching lines @@
   bool get isEmpty {
     return this.length == 0;
   }
 
   bool get isNotEmpty => !isEmpty;
 
   void clear() {
     this.length = 0;
   }
 
-  Iterable<T> get reversed => IterableMixinWorkaround.reversedList(this);
+  Iterable<T> get reversed =>
+      new IterableMixinWorkaround<T>().reversedList(this);
 
   void sort([int compare(T a, T b)]) {
     IterableMixinWorkaround.sortList(this, compare);
   }
 
   void shuffle([Random random]) {
     IterableMixinWorkaround.shuffleList(this, random);
   }
 
   String toString() => ListBase.listToString(this);
 
   Iterator<T> get iterator {
     return new ListIterator<T>(this);
   }
 
   List<T> toList({ bool growable: true }) {
     return new List<T>.from(this, growable: growable);
   }
 
   Set<T> toSet() {
     return new Set<T>.from(this);
   }
 
   Map<int, T> asMap() {
-    return IterableMixinWorkaround.asMapList(this);
+    return new IterableMixinWorkaround<T>().asMapList(this);
   }
 }