Add a getter interceptor to the new interceptor scheme. Also cleanup the "this" that turns into a r…

sdk/lib/_internal/compiler/implementation/js_backend/backend.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;
 
 typedef void Recompile(Element element);
 
 class ReturnInfo {
   HType returnType;
@@ skipping 693 matching lines @@
         ? new CodeEmitterNoEvalTask(compiler, namer, generateSourceMap)
         : new CodeEmitterTask(compiler, namer, generateSourceMap);
     builder = new SsaBuilderTask(this);
     optimizer = new SsaOptimizerTask(this);
     generator = new SsaCodeGeneratorTask(this);
     argumentTypes = new ArgumentTypesRegistry(this);
     fieldTypes = new FieldTypesRegistry(this);
   }
 
   bool isInterceptorClass(Element element) {
+    if (element == null) return false;
     return element == jsStringClass;
   }
 
   void addInterceptedSelector(Selector selector) {
     usedInterceptors.add(selector);
   }
 
   bool shouldInterceptSelector(Selector selector) {
     List<Element> intercepted = interceptedElements[selector.name];
     if (intercepted == null) return false;
     for (Element element in intercepted) {
       if (selector.applies(element, compiler)) return true;
     }
     return false;
   }
 
+  void initializeInterceptorElements() {
+    objectInterceptorClass =
+        compiler.findInterceptor(const SourceString('ObjectInterceptor'));
+    getInterceptorMethod =
+        compiler.findInterceptor(const SourceString('getInterceptor'));
+  }
+
 
   void registerInstantiatedClass(ClassElement cls, Enqueuer enqueuer) {
     ClassElement result = null;
     if (cls == compiler.stringClass) {
       if (jsStringClass == null) {
         jsStringClass =
             compiler.findInterceptor(const SourceString('JSString'));
-        objectInterceptorClass =
-            compiler.findInterceptor(const SourceString('ObjectInterceptor'));
-        getInterceptorMethod =
-            compiler.findInterceptor(const SourceString('getInterceptor'));
+        initializeInterceptorElements();
       }
       result = jsStringClass;
     }
 
     if (result == null) return;
 
     result.forEachMember((_, Element member) {
       List<Element> list = interceptedElements.putIfAbsent(
           member.name, () => new List<Element>());
       list.add(member);
@@ skipping 264 matching lines @@
     print("Inferred return types:");
     print("----------------------");
     dumpReturnTypes();
     print("");
     print("Inferred field types:");
     print("------------------------");
     fieldTypes.dump();
     print("");
   }
 }