Moving ListBase, FixedLengthListMixin and UmodifiableListMixin to collection.

runtime/lib/array.dart

Index: runtime/lib/array.dart
diff --git a/runtime/lib/array.dart b/runtime/lib/array.dart
index e92744c745ae0d5c62f17922c39976b6bbfafb27..aad4e38126f37e07938699b4dc2b071c5bec343f 100644
--- a/runtime/lib/array.dart
+++ b/runtime/lib/array.dart
@@ -174,7 +174,7 @@ class _ObjectArray<E> implements List<E> {
     return this.length == 0;
   }
 
-  Iterable<E> get reversed => new ReversedListIterable<E>(this);
+  Iterable<T> get reversed => IterableMixinWorkaround.reversedList(this);
 
   void sort([int compare(E a, E b)]) {
     IterableMixinWorkaround.sortList(this, compare);
@@ -421,7 +421,7 @@ class _ImmutableArray<E> implements List<E> {
     return this.length == 0;
   }
 
-  Iterable<E> get reversed => new ReversedListIterable<E>(this);
+  Iterable<T> get reversed => IterableMixinWorkaround.reversedList(this);
 
   void sort([int compare(E a, E b)]) {
     throw new UnsupportedError(