Turn getters and setters that we know are not intercepted into regular getter and setter calls.

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 618 matching lines @@
   ClassElement jsFunctionClass;
   ClassElement jsNullClass;
   ClassElement jsBoolClass;
   ClassElement objectInterceptorClass;
   Element jsArrayLength;
   Element jsStringLength;
   Element jsArrayRemoveLast;
   Element jsArrayAdd;
   Element jsStringSplit;
   Element jsStringConcat;
+  Element jsStringToString;
   Element getInterceptorMethod;
   Element fixedLengthListConstructor;
   bool seenAnyClass = false;
 
   final Namer namer;
 
   /**
    * Interface used to determine if an object has the JavaScript
    * indexing behavior. The interface is only visible to specific
    * libraries.
@@ skipping 145 matching lines @@
     jsArrayAdd = compiler.lookupElementIn(
         jsArrayClass, const SourceString('add'));
 
     jsStringClass.ensureResolved(compiler);
     jsStringLength = compiler.lookupElementIn(
         jsStringClass, const SourceString('length'));
     jsStringSplit = compiler.lookupElementIn(
         jsStringClass, const SourceString('split'));
     jsStringConcat = compiler.lookupElementIn(
         jsStringClass, const SourceString('concat'));
+    jsStringToString = compiler.lookupElementIn(
+        jsStringClass, const SourceString('toString'));
 
     for (ClassElement cls in classes) {
       if (cls != null) interceptedClasses[cls] = null;
     }
   }
 
   void addInterceptors(ClassElement cls, Enqueuer enqueuer) {
     if (enqueuer.isResolutionQueue) {
       cls.ensureResolved(compiler);
       cls.forEachMember((ClassElement classElement, Element member) {
@@ skipping 383 matching lines @@
   }
 
   Element getSetRuntimeTypeInfo() {
     return compiler.findHelper(const SourceString('setRuntimeTypeInfo'));
   }
 
   Element getGetRuntimeTypeInfo() {
     return compiler.findHelper(const SourceString('getRuntimeTypeInfo'));
   }
 }