Put back optimization on fixed-size array.

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 637 matching lines @@
 
   ClassElement jsStringClass;
   ClassElement jsArrayClass;
   ClassElement jsNumberClass;
   ClassElement jsIntClass;
   ClassElement jsDoubleClass;
   ClassElement jsFunctionClass;
   ClassElement jsNullClass;
   ClassElement jsBoolClass;
   ClassElement objectInterceptorClass;
-  ClassElement listImplementation;
   Element jsArrayLength;
   Element jsStringLength;
   Element getInterceptorMethod;
   bool _interceptorsAreInitialized = false;
 
   final Namer namer;
 
   /**
    * Interface used to determine if an object has the JavaScript
    * indexing behavior. The interface is only visible to specific
@@ skipping 113 matching lines @@
     jsFunctionClass =
         compiler.findInterceptor(const SourceString('JSFunction'));
     jsBoolClass =
         compiler.findInterceptor(const SourceString('JSBool'));
     jsArrayClass.ensureResolved(compiler);
     jsArrayLength =
         jsArrayClass.lookupLocalMember(const SourceString('length'));
     jsStringClass.ensureResolved(compiler);
     jsStringLength =
         jsStringClass.lookupLocalMember(const SourceString('length'));
-    listImplementation =
-        compiler.coreLibrary.find(const SourceString('ListImplementation'));
   }
 
   void addInterceptors(ClassElement cls) {
     cls.ensureResolved(compiler);
     cls.forEachMember((ClassElement classElement, Element member) {
         Set<Element> set = interceptedElements.putIfAbsent(
             member.name, () => new Set<Element>());
         set.add(member);
       },
       includeSuperMembers: true);
@@ skipping 13 matching lines @@
         enqueuer.registerInstantiatedClass(jsNullClass);
       }
       if (jsFunctionClass != null) {
         addInterceptors(jsFunctionClass);
         enqueuer.registerInstantiatedClass(jsFunctionClass);
       }
       enqueuer.addToWorkList(getInterceptorMethod);
     }
     if (cls == compiler.stringClass) {
       result = jsStringClass;
-    } else if (cls == compiler.listClass || cls == listImplementation) {
+    } else if (cls == compiler.listClass) {
       result = jsArrayClass;
     } else if (cls == compiler.intClass) {
       result = jsIntClass;
     } else if (cls == compiler.doubleClass) {
       result = jsDoubleClass;
     } else if (cls == compiler.functionClass) {
       result = jsFunctionClass;
     } else if (cls == compiler.boolClass) {
       result = jsBoolClass;
     }
@@ skipping 265 matching lines @@
     print("Inferred return types:");
     print("----------------------");
     dumpReturnTypes();
     print("");
     print("Inferred field types:");
     print("------------------------");
     fieldTypes.dump();
     print("");
   }
 }