dart2js allocation tweaks

pkg/compiler/lib/src/world.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.
 
 library dart2js.world;
 
 import 'closure.dart' show ClosureClassElement, SynthesizedCallMethodElementX;
 import 'common.dart';
 import 'constants/constant_system.dart';
 import 'common_elements.dart' show CommonElements;
@@ skipping 1020 matching lines @@
         }
       } else {
         sideEffects.add(getSideEffectsOfElement(e));
       }
     }
     return sideEffects;
   }
 
   SideEffects getSideEffectsOfElement(Entity element) {
     assert(_checkEntity(element));
-    return _sideEffects.putIfAbsent(element, () {
-      return new SideEffects();
-    });
+    return _sideEffects.putIfAbsent(element, _makeSideEffects);
   }
 
+  static _makeSideEffects() => new SideEffects();
+
   @override
   SideEffects getCurrentlyKnownSideEffects(Entity element) {
     return getSideEffectsOfElement(element);
   }
 
   void registerSideEffects(Entity element, SideEffects effects) {
     assert(_checkEntity(element));
     if (_sideEffectsFreeElements.contains(element)) return;
     _sideEffects[element] = effects;
   }
@@ skipping 283 matching lines @@
   @override
   void registerClosureClass(ClassElement cls) {
     throw new UnimplementedError('KernelClosedWorld.registerClosureClass');
   }
 
   @override
   bool hasElementIn(ClassEntity cls, Selector selector, Entity element) {
     throw new UnimplementedError('KernelClosedWorld.hasElementIn');
   }
 }