Reapply 'Add runtimeType() to Object which returns canonicalized instances of Type'.

lib/compiler/implementation/enqueue.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.
 
 class EnqueueTask extends CompilerTask {
   final Enqueuer codegen;
   final Enqueuer resolution;
 
   String get name => 'Enqueue';
 
@@ skipping 89 matching lines @@
     }
     if (elements === null) {
       elements = getCachedElements(element);
     }
     if (isResolutionQueue) {
       compiler.world.registerUsedElement(element);
     }
 
     queue.add(new WorkItem(element, elements, itemCompilationContextCreator()));
 
+    // Enable runtime type support if we discover a method called runtimeType.
+    if (element.isFunction() && element.name == Compiler.RUNTIME_TYPE) {
+      compiler.enabledRuntimeType = true;
+    }
+
     // Enable isolate support if we start using something from the
     // isolate library.
     LibraryElement library = element.getLibrary();
     if (!compiler.hasIsolateSupport()
         && library.uri.toString() == 'dart:isolate') {
       compiler.enableIsolateSupport(library);
     }
   }
 
   void eagerRecompile(Element element) {
@@ skipping 226 matching lines @@
   void registerIsCheck(DartType type) {
     universe.isChecks.add(type);
   }
 
   void forEach(f(WorkItem work)) {
     while (!queue.isEmpty()) {
       f(queue.removeLast()); // TODO(kasperl): Why isn't this removeFirst?
     }
   }
 }