Hydrogenize (and share) part of StoreTransition handler as a StoreTransitionStub.

src/x64/interface-descriptors-x64.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/v8.h"
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/interface-descriptors.h"
 
@@ skipping 11 matching lines @@
 
 
 const Register VectorLoadICDescriptor::VectorRegister() { return rbx; }
 
 
 const Register StoreDescriptor::ReceiverRegister() { return rdx; }
 const Register StoreDescriptor::NameRegister() { return rcx; }
 const Register StoreDescriptor::ValueRegister() { return rax; }
 
 
-const Register ExtendStorageDescriptor::MapRegister() { return rbx; }
+const Register StoreTransitionDescriptor::MapRegister() { return rbx; }
 
 
 const Register ElementTransitionAndStoreDescriptor::MapRegister() {
   return rbx;
 }
 
 
 const Register InstanceofDescriptor::left() { return rax; }
 const Register InstanceofDescriptor::right() { return rdx; }
 
@@ skipping 256 matching lines @@
       Representation::Tagged(),    // call_data
       Representation::Tagged(),    // holder
       Representation::External(),  // api_function_address
   };
   data->Initialize(arraysize(registers), registers, representations);
 }
 }
 }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64