dart2js: only allocate one closure in 'setupClass' of the new emitter.

pkg/compiler/lib/src/js_emitter/new_emitter/model_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.
 
 library dart2js.new_js_emitter.model_emitter;
 
 import '../../dart2jslib.dart' show Compiler;
 import '../../dart_types.dart' show DartType;
 import '../../elements/elements.dart' show ClassElement;
 import '../../js/js.dart' as js;
@@ skipping 823 matching lines @@
           // initialization failed.
           holder[name] = null;
         }
         holder[getterName] = function() { return this[name]; };
       }
       return result;
     };
   }
 
   function setupClass(name, holder, descriptor) {
-    var ensureResolved = function() {
+    var patch = function() {
       var constructor = compileConstructor(name, descriptor);
       holder[name] = constructor;
       constructor.ensureResolved = function() { return this; };
-      return constructor;
-    };
-
-    var patch = function() {
-      var constructor = ensureResolved();
+      if (this === patch) return constructor;  // Was used as "ensureResolved".
       var object = new constructor();
       constructor.apply(object, arguments);
       return object;
     };
 
-    // We store the ensureResolved function on the patch function to make it
+    // We store the patch function on itself to make it
     // possible to resolve superclass references without constructing instances.
-    patch.ensureResolved = ensureResolved;
+    patch.ensureResolved = patch;
     holder[name] = patch;
   }
 
   #tearOff;
 
   #parseFunctionDescriptor;
 
   function compileConstructor(name, descriptor) {
     descriptor = compile(name, descriptor);
     var prototype = determinePrototype(descriptor);
@@ skipping 107 matching lines @@
 
   var end = Date.now();
   // print('Setup: ' + (end - start) + ' ms.');
 
   #invokeMain;  // Start main.
 
 }(Date.now(), #code)
 }""";
 
 }