remove some calls to to-be-deprecated v8::Value::To* functions

extensions/renderer/document_custom_bindings.cc

 // Copyright 2014 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 "extensions/renderer/document_custom_bindings.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "extensions/renderer/script_context.h"
@@ skipping 12 matching lines @@
 
 // Attach an event name to an object.
 void DocumentCustomBindings::RegisterElement(
     const v8::FunctionCallbackInfo<v8::Value>& args) {
   if (args.Length() != 2 || !args[0]->IsString() || !args[1]->IsObject()) {
     NOTREACHED();
     return;
   }
 
   std::string element_name(*v8::String::Utf8Value(args[0]));
-  v8::Local<v8::Object> options = args[1]->ToObject();
+  v8::Local<v8::Object> options = v8::Local<v8::Object>::Cast(args[1]);
 
   blink::WebExceptionCode ec = 0;
   blink::WebDocument document = context()->web_frame()->document();
   v8::Handle<v8::Value> constructor = document.registerEmbedderCustomElement(
       blink::WebString::fromUTF8(element_name), options, ec);
   args.GetReturnValue().Set(constructor);
 }
 
 }  // namespace extensions