Implement getRange (returning an Iterable).

runtime/lib/array.dart

Index: runtime/lib/array.dart
diff --git a/runtime/lib/array.dart b/runtime/lib/array.dart
index 37efab9c7f4d7d7ebba390d179f0a7049ac21d89..2478686b5aa44cdc324ffb97ca7b9119b801f570 100644
--- a/runtime/lib/array.dart
+++ b/runtime/lib/array.dart
@@ -60,6 +60,10 @@ class _ObjectArray<E> implements List<E> {
         "Cannot remove element of a non-extendable array");
   }
 
+  Iterable<E> getRange(int start, [int end]) {
+    return IterableMixinWorkaround.getRangeList(this, start, end);
+  }
+
   // List interface.
   void setRange(int start, int length, List<E> from, [int startFrom = 0]) {
     if (length < 0) {
@@ -94,8 +98,6 @@ class _ObjectArray<E> implements List<E> {
     return list;
   }
 
-  List<E> getRange(int start, int length) => sublist(start, start + length);
-
   // Iterable interface.
 
   bool contains(E element) {
@@ -341,7 +343,9 @@ class _ImmutableArray<E> implements List<E> {
     return list;
   }
 
-  List<E> getRange(int start, int length) => sublist(start, start + length);
+  Iterable<E> getRange(int start, int end) {
+    return IterableMixinWorkaround.getRangeList(this, start, end);
+  }
 
   // Collection interface.