Remove BackendClasses and JavaScriptBackendClasses.

pkg/compiler/lib/src/inferrer/node_tracer.dart

 // Copyright (c) 2013, 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.
 
 library compiler.src.inferrer.node_tracer;
 
 import '../common/names.dart' show Identifiers;
 import '../compiler.dart' show Compiler;
 import '../elements/elements.dart';
 import '../types/types.dart' show ContainerTypeMask, MapTypeMask;
@@ skipping 379 matching lines @@
     }
   }
 
   /**
    * Check whether element is the parameter of a list adding method.
    * The definition of what a list adding method is has to stay in sync with
    * [mightAddToContainer].
    */
   bool isParameterOfListAddingMethod(Element element) {
     if (!element.isRegularParameter) return false;
-    if (element.enclosingClass != compiler.backend.backendClasses.listClass) {
+    if (element.enclosingClass != compiler.commonElements.jsArrayClass) {
       return false;
     }
     String name = element.enclosingElement.name;
     return (name == '[]=') || (name == 'add') || (name == 'insert');
   }
 
   /**
    * Check whether element is the parameter of a list adding method.
    * The definition of what a list adding method is has to stay in sync with
    * [isIndexSetKey] and [isIndexSetValue].
    */
   bool isParameterOfMapAddingMethod(Element element) {
     if (!element.isRegularParameter) return false;
-    if (element.enclosingClass != compiler.backend.backendClasses.mapClass) {
+    if (element.enclosingClass != compiler.commonElements.mapLiteralClass) {
       return false;
     }
     String name = element.enclosingElement.name;
     return (name == '[]=');
   }
 
   bool isClosure(Element element) {
     if (!element.isFunction) return false;
 
     /// Creating an instance of a class that implements [Function] also
@@ skipping 35 matching lines @@
     }
     if (isParameterOfListAddingMethod(element) ||
         isParameterOfMapAddingMethod(element)) {
       // These elements are being handled in
       // [visitDynamicCallSiteTypeInformation].
       return;
     }
     addNewEscapeInformation(info);
   }
 }