Add List.reversed to give a reverse fixed-length view of a list.

runtime/lib/array.dart

Index: runtime/lib/array.dart
diff --git a/runtime/lib/array.dart b/runtime/lib/array.dart
index 165ba64812fe23e8c34f4db3210345b0c9ec585f..7dd70bc712533cf183f7c1cb6408486e67002a9b 100644
--- a/runtime/lib/array.dart
+++ b/runtime/lib/array.dart
@@ -154,6 +154,8 @@ class _ObjectArray<E> implements List<E> {
     return this.length == 0;
   }
 
+  List<E> get reversed => new ReversedList<E>(this, 0, length);
+
   void sort([int compare(E a, E b)]) {
     if (compare == null) compare = Comparable.compare;
     _Sort.sort(this, compare);
@@ -383,6 +385,8 @@ class _ImmutableArray<E> implements List<E> {
     return this.length == 0;
   }
 
+  List<E> get reversed => new ReversedList<E>(this, 0, length);
+
   void sort([int compare(E a, E b)]) {
     throw new UnsupportedError(
         "Cannot modify an immutable array");