Have Document::timing() / Document::contextFeatures() return a reference

Source/core/dom/Document.cpp

Index: Source/core/dom/Document.cpp
diff --git a/Source/core/dom/Document.cpp b/Source/core/dom/Document.cpp
index 92f5c6dd47b0fc04183972ac590261bdfc925442..e14d9cbc60fdd3e94e3e0175d2d709299d327664 100644
--- a/Source/core/dom/Document.cpp
+++ b/Source/core/dom/Document.cpp
@@ -2710,7 +2710,7 @@ void Document::setURL(const KURL& url)
 
     m_url = newURL;
     updateBaseURL();
-    contextFeatures()->urlDidChange(this);
+    contextFeatures().urlDidChange(this);
 }
 
 void Document::updateBaseURL()
@@ -5127,9 +5127,9 @@ void Document::decrementActiveParserCount()
     frame()->loader().checkLoadComplete();
 }
 
-void Document::setContextFeatures(PassRefPtr<ContextFeatures> features)
+void Document::setContextFeatures(ContextFeatures& features)
 {
-    m_contextFeatures = features;
+    m_contextFeatures = PassRefPtr<ContextFeatures>(features);
 }
 
 static RenderObject* nearestCommonHoverAncestor(RenderObject* obj1, RenderObject* obj2)