Cleanup after the interceptor refactoring work, and add a new SSA instruction for an interceptor, s…

sdk/lib/_internal/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.
 
 part of dart2js;
 
 class EnqueueTask extends CompilerTask {
   final Enqueuer codegen;
   final Enqueuer resolution;
 
@@ skipping 386 matching lines @@
   }
 
   String toString() => 'Enqueuer($name)';
 
   void logSummary(log(message)) {
     log(isResolutionQueue
         ? 'Resolved ${resolvedElements.length} elements.'
         : 'Compiled ${universe.generatedCode.length} methods.');
     nativeEnqueuer.logSummary(log);
   }
-
-  registerUsedSelector(Selector selector) {
-    Element interceptor = compiler.backend.getInterceptor(selector);
-    if (interceptor != null) {
-      registerStaticUse(interceptor);
-    }
-  }
 }