Introduce BackendImpact to separate enqueueing from data.

pkg/compiler/lib/src/js_emitter/class_stub_generator.dart

 // Copyright (c) 2014, 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.js_emitter;
 
 class ClassStubGenerator {
   final Namer namer;
   final Compiler compiler;
   final JavaScriptBackend backend;
@@ skipping 149 matching lines @@
         js('''this.#noSuchMethodName(#receiver,
                     #createInvocationMirror(#methodName,
                                             #internalName,
                                             #type,
                                             #arguments,
                                             #namedArguments))''',
            {'receiver': isIntercepted ? r'$receiver' : 'this',
             'noSuchMethodName': namer.noSuchMethodName,
             'createInvocationMirror':
                 backend.emitter.staticFunctionAccess(
-                    backend.getCreateInvocationMirror()),
+                    backend.helpers.createInvocationMirror),
             'methodName':
                 js.quoteName(compiler.enableMinification
                     ? internalName : methodName),
             'internalName': js.quoteName(internalName),
             'type': js.number(type),
             'arguments':
                 new jsAst.ArrayInitializer(parameterNames.map(js).toList()),
             'namedArguments': new jsAst.ArrayInitializer(argNames)});
 
     jsAst.Expression function;
@@ skipping 94 matching lines @@
           ? function() {
               if (cache === void 0) cache = #tearOff(
                   this, funcs, reflectionInfo, true, [], name).prototype;
               return cache;
             }
           : tearOffGetter(funcs, reflectionInfo, name, isIntercepted);
     }''',  {'tearOff': tearOffAccessExpression});
 
   return <jsAst.Statement>[tearOffGetter, tearOff];
 }