Implement accessing lazily initialized static fields.

dart/sdk/lib/_internal/compiler/implementation/js_backend/emitter.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.
 
 part of js_backend;
 
 /**
  * A function element that represents a closure call. The signature is copied
  * from the given element.
  */
@@ skipping 866 matching lines @@
                               'getterName', 'lazyValue'];
     return js.fun(parameters, [
       js('var getter = new Function("{ return this." + fieldName + ";}")'),
     ]..addAll(addLazyInitializerLogic())
     );
   }
 
   List addLazyInitializerLogic() {
     String isolate = namer.CURRENT_ISOLATE;
     String cyclicThrow = namer.isolateAccess(backend.getCyclicThrowHelper());
+    var lazies = [];
+    if (backend.rememberLazies) {
+      lazies = [
+          js.if_('!init.lazies', js('init.lazies = {}')),
+          js('init.lazies[fieldName] = getterName')];
+    }
 
-    return [
+    return lazies..addAll([
       js('var sentinelUndefined = {}'),
       js('var sentinelInProgress = {}'),
       js('prototype[fieldName] = sentinelUndefined'),
 
       // prototype[getterName] = function()
       js('prototype[getterName] = #', js.fun([], [
         js('var result = $isolate[fieldName]'),
 
         // try
         js.try_([
@@ skipping 22 matching lines @@
             )
           ]),
 
           // return result;
           js.return_('result')
 
         ], finallyPart: [
           js('$isolate[getterName] = getter')
         ])
       ]))
-    ];
+    ]);
   }
 
   List buildDefineClassAndFinishClassFunctionsIfNecessary() {
     if (!needsDefineClass) return [];
     return defineClassFunction
     ..addAll(buildProtoSupportCheck())
     ..addAll([
       js('$finishClassesName = #', finishClassesFunction)
     ]);
   }
@@ skipping 2945 matching lines @@
 
 const String HOOKS_API_USAGE = """
 // The code supports the following hooks:
 // dartPrint(message)   - if this function is defined it is called
 //                        instead of the Dart [print] method.
 // dartMainRunner(main) - if this function is defined, the Dart [main]
 //                        method will not be invoked directly.
 //                        Instead, a closure that will invoke [main] is
 //                        passed to [dartMainRunner].
 """;