Make DOMWrapperWorld::current() return a reference instead of a pointer

Source/bindings/v8/MIDIAccessResolver.cpp

 // 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 "config.h"
 #include "bindings/v8/MIDIAccessResolver.h"
 
 #include "bindings/v8/ScriptPromiseResolver.h"
 #include "bindings/v8/V8Binding.h"
 #include <v8.h>
 
 namespace WebCore {
 
 MIDIAccessResolver::MIDIAccessResolver(PassRefPtr<ScriptPromiseResolver> resolver, v8::Isolate* isolate)
     : m_resolver(resolver)
     , m_world(DOMWrapperWorld::current(isolate))
 {
 }
 
 MIDIAccessResolver::~MIDIAccessResolver()
 {
 }
 
 void MIDIAccessResolver::resolve(MIDIAccess* access, ExecutionContext* executionContext)
 {
     v8::HandleScope handleScope(toIsolate(executionContext));
-    v8::Context::Scope contextScope(toV8Context(executionContext, m_world.get()));
+    v8::Context::Scope contextScope(toV8Context(executionContext, *m_world));
 
     m_resolver->resolve(access, executionContext);
 }
 
 void MIDIAccessResolver::reject(DOMError* error, ExecutionContext* executionContext)
 {
     v8::HandleScope handleScope(toIsolate(executionContext));
-    v8::Context::Scope contextScope(toV8Context(executionContext, m_world.get()));
+    v8::Context::Scope contextScope(toV8Context(executionContext, *m_world));
 
     m_resolver->reject(error, executionContext);
 }
 
 } // namespace WebCore