Make DocumentLoader::timing return a reference

Source/core/timing/Performance.cpp

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2012 Intel Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 31 matching lines @@
 #include "platform/weborigin/SecurityOrigin.h"
 #include "wtf/CurrentTime.h"
 
 namespace blink {
 
 static const size_t defaultResourceTimingBufferSize = 150;
 
 Performance::Performance(LocalFrame* frame)
     : DOMWindowProperty(frame)
     , m_resourceTimingBufferSize(defaultResourceTimingBufferSize)
-    , m_referenceTime(frame && frame->host() ? frame->document()->loader()->timing()->referenceMonotonicTime() : 0.0)
+    , m_referenceTime(frame && frame->host() ? frame->document()->loader()->timing().referenceMonotonicTime() : 0.0)
     , m_userTiming(nullptr)
 {
 }
 
 Performance::~Performance()
 {
 }
 
 const AtomicString& Performance::interfaceName() const
 {
@@ skipping 219 matching lines @@
 {
     visitor->trace(m_navigation);
     visitor->trace(m_timing);
     visitor->trace(m_resourceTimingBuffer);
     visitor->trace(m_userTiming);
     EventTargetWithInlineData::trace(visitor);
     DOMWindowProperty::trace(visitor);
 }
 
 } // namespace blink