Small changes to get the compilation size of code importing dart:html shorter.

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 78 matching lines @@
       if (isResolutionQueue && getCachedElements(element) !== null) return;
       compiler.internalErrorOnElement(element, "Work list is closed.");
     }
     if (!isResolutionQueue &&
         element.kind === ElementKind.GENERATIVE_CONSTRUCTOR) {
       registerInstantiatedClass(element.getEnclosingClass());
     }
     if (elements === null) {
       elements = getCachedElements(element);
     }
+
     queue.add(new WorkItem(element, elements, itemCompilationContextCreator()));
+
+    // 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) {
     universe.generatedCode.remove(element);
     universe.generatedBailoutCode.remove(element);
     addToWorkList(element);
   }
 
   bool canBeRecompiled(Element element) {
     // Only member functions can be recompiled. An exception to this is members
@@ skipping 219 matching lines @@
   void registerIsCheck(Element element) {
     universe.isChecks.add(element);
   }
 
   void forEach(f(WorkItem work)) {
     while (!queue.isEmpty()) {
       f(queue.removeLast()); // TODO(kasperl): Why isn't this removeFirst?
     }
   }
 }