Revert "Fix casts and type assertions on mixins used in native classes."

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 ResolutionEnqueuer resolution;
   final CodegenEnqueuer codegen;
 
@@ skipping 477 matching lines @@
    * If a factory constructor is used with type arguments, we lose track
    * which arguments could be used to create instances of classes that use their
    * type variables as expressions, so we have to remember if we saw such a use.
    */
   void registerFactoryWithTypeArguments(TreeElements elements) {
     universe.usingFactoryWithTypeArguments = true;
   }
 
   void registerAsCheck(DartType type, TreeElements elements) {
     registerIsCheck(type, elements);
-    compiler.backend.registerAsCheck(type, this, elements);
+    compiler.backend.registerAsCheck(type, elements);
   }
 
   void registerGenericCallMethod(Element element, TreeElements elements) {
     compiler.backend.registerGenericCallMethod(element, this, elements);
     universe.genericCallMethods.add(element);
   }
 
   void registerBoundClosure() {
     registerInstantiatedClass(compiler.boundClosureClass,
                               // Precise dependency is not important here.
@@ skipping 216 matching lines @@
     while(!queue.isEmpty) {
       // TODO(johnniwinther): Find an optimal process order for codegen.
       f(queue.removeLast());
     }
   }
 
   void _logSpecificSummary(log(message)) {
     log('Compiled ${generatedCode.length} methods.');
   }
 }