Replace Handle<> with Local in remaining gin/*

gin/context_holder.cc

 // Copyright 2013 The Chromium 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 "gin/public/context_holder.h"
 
 #include "base/logging.h"
 #include "gin/per_context_data.h"
 
 namespace gin {
 
 ContextHolder::ContextHolder(v8::Isolate* isolate)
     : isolate_(isolate) {
 }
 
 ContextHolder::~ContextHolder() {
   // PerContextData needs to be destroyed before the context.
   data_.reset();
 }
 
-void ContextHolder::SetContext(v8::Handle<v8::Context> context) {
+void ContextHolder::SetContext(v8::Local<v8::Context> context) {
   DCHECK(context_.IsEmpty());
   context_.Reset(isolate_, context);
   data_.reset(new PerContextData(this, context));
 }
 
 }  // namespace gin