Fix https://code.google.com/p/dart/issues/detail?id=15132, by not doing load elimination on typed a…

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;
 
 class JavaScriptItemCompilationContext extends ItemCompilationContext {
   final Set<HInstruction> boundsChecked = new Set<HInstruction>();
   final Set<HInstruction> allocatedFixedLists = new Set<HInstruction>();
 }
@@ skipping 1814 matching lines @@
 
   bool isTypedArray(TypeMask mask) {
     // Just checking for [:TypedData:] is not sufficient, as it is an
     // abstract class any user-defined class can implement. So we also
     // check for the interface [JavaScriptIndexingBehavior].
     return compiler.typedDataClass != null
         && mask.satisfies(compiler.typedDataClass, compiler)
         && mask.satisfies(jsIndexingBehaviorInterface, compiler);
   }
 
+  bool couldBeTypedArray(TypeMask mask) {
+    TypeMask indexing = new TypeMask.subtype(jsIndexingBehaviorInterface);
+    // Checking if [mask] contains [indexing] means that we want to
+    // know if [mask] is not a more specific type than [indexing].
+    return isTypedArray(mask) || mask.containsMask(indexing, compiler);
+  }
+
   /// Called when [enqueuer] is empty, but before it is closed.
   void onQueueEmpty(Enqueuer enqueuer) {
     if (!enqueuer.isResolutionQueue && preMirrorsMethodCount == 0) {
       preMirrorsMethodCount = generatedCode.length;
     }
 
     if (isTreeShakingDisabled) enqueuer.enqueueEverything();
 
     if (mustPreserveNames) compiler.log('Preserving names.');
 
@@ skipping 68 matching lines @@
     copy(constant.values);
     copy(constant.protoValue);
     copy(constant);
   }
 
   void visitConstructed(ConstructedConstant constant) {
     copy(constant.fields);
     copy(constant);
   }
 }