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

Source/core/dom/ContainerNodeAlgorithms.h

Index: Source/core/dom/ContainerNodeAlgorithms.h
diff --git a/Source/core/dom/ContainerNodeAlgorithms.h b/Source/core/dom/ContainerNodeAlgorithms.h
index ebd52637d6f5ee3a542477c2d58e09d30707e169..e9ff73f7fad5a5ddb7c7f955deb4b2299099682d 100644
--- a/Source/core/dom/ContainerNodeAlgorithms.h
+++ b/Source/core/dom/ContainerNodeAlgorithms.h
@@ -213,9 +213,9 @@ inline void ChildNodeInsertionNotifier::notify(Node* node)
 {
     ASSERT(!NoEventDispatchAssertion::isEventDispatchForbidden());
 
-    InspectorInstrumentation::didInsertDOMNode(node->document(), node);
+    InspectorInstrumentation::didInsertDOMNode(&node->document(), node);
 
-    RefPtr<Document> protectDocument(node->document());
+    RefPtr<Document> protectDocument(&node->document());
     RefPtr<Node> protectNode(node);
 
     if (m_insertionPoint->inDocument())
@@ -250,7 +250,7 @@ inline void ChildNodeRemovalNotifier::notify(Node* node)
 {
     if (node->inDocument()) {
         notifyNodeRemovedFromDocument(node);
-        node->document()->notifyRemovePendingSheetIfNeeded();
+        node->document().notifyRemovePendingSheetIfNeeded();
     } else if (node->isContainerNode())
         notifyNodeRemovedFromTree(toContainerNode(node));
 }