Simplify runtime type support.

sdk/lib/_internal/compiler/implementation/lib/interceptors.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.
 
 #library('dart:_interceptors');
 
 #import('dart:collection');
 
 /**
  * The interceptor class for [String]. The compiler recognizes this
@@ skipping 684 matching lines @@
     return getOrCreateCachedRuntimeType('int');
   } else if (receiver is String) {
     return getOrCreateCachedRuntimeType('String');
   } else if (receiver is double) {
     return getOrCreateCachedRuntimeType('double');
   } else if (receiver is bool) {
     return getOrCreateCachedRuntimeType('bool');
   } else if (receiver == null) {
     return getOrCreateCachedRuntimeType('Null');
   } else if (isJsArray(receiver)) {
-    return getOrCreateCachedRuntimeType('List');
+    return getOrCreateCachedRuntimeType(getRuntimeTypeString(receiver));
   } else {
     return UNINTERCEPTED(receiver.runtimeType);
   }
 }
 
 // TODO(lrn): These getters should be generated automatically for all
 // intercepted methods.
 get$toString(receiver) => () => toString(receiver);