Move registering of interceptors to the JsBackend.

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 341 matching lines @@
     universe.isChecks.add(type);
   }
 
   void forEach(f(WorkItem work)) {
     while (!queue.isEmpty()) {
       f(queue.removeLast()); // TODO(kasperl): Why isn't this removeFirst?
     }
   }
 
   String toString() => 'Enqueuer($name)';
+
+  registerUsedSelector(Selector selector) {
+    Element interceptor = compiler.backend.getInterceptor(selector);
+    if (interceptor != null) {
+      registerStaticUse(interceptor);
+    }
+  }
 }