Revert "Remove Object.dynamic."

lib/compiler/implementation/lib/interceptors.dart

Index: lib/compiler/implementation/lib/interceptors.dart
diff --git a/lib/compiler/implementation/lib/interceptors.dart b/lib/compiler/implementation/lib/interceptors.dart
index 17f8e51fa7534f2f73ef37a3575a80029513cf7a..8ca99f3a3151afe080eb7ec529b72c4cebdb34b0 100644
--- a/lib/compiler/implementation/lib/interceptors.dart
+++ b/lib/compiler/implementation/lib/interceptors.dart
@@ -598,7 +598,7 @@ trim(receiver) {
 
 /**
  * This is the [Jenkins hash function][1] but using masking to keep
- * values in SMI range.
+ * values in SMI range. 
  *
  * [1]: http://en.wikipedia.org/wiki/Jenkins_hash_function
  */
@@ -619,6 +619,9 @@ hashCode(receiver) {
   return 0x1fffffff & (hash + JS('int', @'# << #', 0x00003fff & hash, 15));
 }
 
+// TODO(ahe): Dynamic may be overridden.
+get$dynamic(receiver) => receiver;
+
 charCodes(receiver) {
   if (receiver is !String) return UNINTERCEPTED(receiver.charCodes());
   int len = receiver.length;