Have Node::document() return a reference instead of a pointer

Source/core/dom/shadow/ElementShadow.cpp

Index: Source/core/dom/shadow/ElementShadow.cpp
diff --git a/Source/core/dom/shadow/ElementShadow.cpp b/Source/core/dom/shadow/ElementShadow.cpp
index 1224962e4b06c4cba455aeb886742d57df4ee9e4..d6995115dac4642a4504c63d62f8c648468edc92 100644
--- a/Source/core/dom/shadow/ElementShadow.cpp
+++ b/Source/core/dom/shadow/ElementShadow.cpp
@@ -57,7 +57,7 @@ ElementShadow::~ElementShadow()
 
 ShadowRoot* ElementShadow::addShadowRoot(Element* shadowHost, ShadowRoot::ShadowRootType type)
 {
-    RefPtr<ShadowRoot> shadowRoot = ShadowRoot::create(shadowHost->document(), type);
+    RefPtr<ShadowRoot> shadowRoot = ShadowRoot::create(&shadowHost->document(), type);
 
     shadowRoot->setParentOrShadowHostNode(shadowHost);
     shadowRoot->setParentTreeScope(shadowHost->treeScope());
@@ -82,14 +82,14 @@ void ElementShadow::removeAllShadowRoots()
 
     while (RefPtr<ShadowRoot> oldRoot = m_shadowRoots.head()) {
         InspectorInstrumentation::willPopShadowRoot(shadowHost, oldRoot.get());
-        shadowHost->document()->removeFocusedElementOfSubtree(oldRoot.get());
+        shadowHost->document().removeFocusedElementOfSubtree(oldRoot.get());
 
         if (oldRoot->attached())
             oldRoot->detach();
 
         m_shadowRoots.removeHead();
         oldRoot->setParentOrShadowHostNode(0);
-        oldRoot->setParentTreeScope(shadowHost->document());
+        oldRoot->setParentTreeScope(&shadowHost->document());
         oldRoot->setPrev(0);
         oldRoot->setNext(0);
         ChildNodeRemovalNotifier(shadowHost).notify(oldRoot.get());