[turbofan] Add support for transitioning stores to double fields.

src/code-stubs.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/code-stubs.h"
 
 #include <sstream>
 
 #include "src/bootstrapper.h"
 #include "src/factory.h"
@@ skipping 726 matching lines @@
 }
 
 
 void AllocateHeapNumberStub::InitializeDescriptor(
     CodeStubDescriptor* descriptor) {
   descriptor->Initialize(
       Runtime::FunctionForId(Runtime::kAllocateHeapNumber)->entry);
 }
 
 
+void AllocateMutableHeapNumberStub::InitializeDescriptor(
+    CodeStubDescriptor* descriptor) {
+  descriptor->Initialize();
+}
+
+
 void AllocateInNewSpaceStub::InitializeDescriptor(
     CodeStubDescriptor* descriptor) {
   descriptor->Initialize();
 }
 
 
 void CompareNilICStub::InitializeDescriptor(CodeStubDescriptor* descriptor) {
   descriptor->Initialize(FUNCTION_ADDR(Runtime_CompareNilIC_Miss));
   descriptor->SetMissHandler(ExternalReference(
       Runtime::FunctionForId(Runtime::kCompareNilIC_Miss), isolate()));
@@ skipping 308 matching lines @@
 
   if (type->Is(Type::UntaggedPointer())) {
     return Representation::External();
   }
 
   DCHECK(!type->Is(Type::Untagged()));
   return Representation::Tagged();
 }
 }  // namespace internal
 }  // namespace v8