Use Object.create instead of a tmp-function.

dart/pkg/compiler/lib/src/js_emitter/old_emitter/emitter.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 OldEmitter implements Emitter {
   final Compiler compiler;
   final CodeEmitterTask task;
@@ skipping 288 matching lines @@
         generateAccessorFunction,
         js('$generateAccessorHolder = generateAccessor'),
         new jsAst.FunctionDeclaration(
             new jsAst.VariableDeclaration('defineClass'), defineClass) ];
   }
 
   /** Needs defineClass to be defined. */
   jsAst.Expression buildInheritFrom() {
     jsAst.Expression result = js(r'''
         function() {
-          function tmp() {}
           var hasOwnProperty = Object.prototype.hasOwnProperty;
           return function (constructor, superConstructor) {
-            tmp.prototype = superConstructor.prototype;
-            var object = new tmp();
+            var object = Object.create(superConstructor.prototype);
             var properties = constructor.prototype;
             for (var member in properties) {
               if (hasOwnProperty.call(properties, member)) {
                 object[member] = properties[member];
               }
             }
             object.constructor = constructor;
             constructor.prototype = object;
             return object;
           };
@@ skipping 1685 matching lines @@
     for (Element element in compiler.enqueuer.codegen.newlyEnqueuedElements) {
       if (element.isInstanceMember) {
         cachedClassBuilders.remove(element.enclosingClass);
 
         nativeEmitter.cachedBuilders.remove(element.enclosingClass);
 
       }
     }
   }
 }