Handle Performance object creation on loader-less Documents.

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 21 matching lines @@
 #include "config.h"
 #include "core/timing/Performance.h"
 
 #include "core/dom/Document.h"
 #include "core/frame/LocalFrame.h"
 #include "core/loader/DocumentLoader.h"
 #include "core/timing/PerformanceTiming.h"
 
 namespace blink {
 
+static double toTimeOrigin(LocalFrame* frame)
+{
+    if (!frame)
+        return 0.0;
+
+    Document* document = frame->document();
+    if (!document)
+        return 0.0;
+
+    DocumentLoader* loader = document->loader();
+    if (!loader)
+        return 0.0;
+
+    return loader->timing().referenceMonotonicTime();
+}
+
 Performance::Performance(LocalFrame* frame)
-    : PerformanceBase(frame && frame->host() ? frame->document()->loader()->timing().referenceMonotonicTime() : 0.0)
+    : PerformanceBase(toTimeOrigin(frame))
     , DOMWindowProperty(frame)
 {
 }
 
 Performance::~Performance()
 {
 }
 
 ExecutionContext* Performance::executionContext() const
 {
@@ skipping 25 matching lines @@
 
 DEFINE_TRACE(Performance)
 {
     visitor->trace(m_navigation);
     visitor->trace(m_timing);
     DOMWindowProperty::trace(visitor);
     PerformanceBase::trace(visitor);
 }
 
 } // namespace blink