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

Source/core/svg/SVGTitleElement.cpp

Index: Source/core/svg/SVGTitleElement.cpp
diff --git a/Source/core/svg/SVGTitleElement.cpp b/Source/core/svg/SVGTitleElement.cpp
index 6f8c58589190605cf2ccd1295f19cfa186f12b2c..f6fad1eae46a5071c31872847ca8da7e06d5ea1e 100644
--- a/Source/core/svg/SVGTitleElement.cpp
+++ b/Source/core/svg/SVGTitleElement.cpp
@@ -44,7 +44,7 @@ Node::InsertionNotificationRequest SVGTitleElement::insertedInto(ContainerNode*
     if (!rootParent->inDocument())
         return InsertionDone;
     if (firstChild())
-        document()->setTitleElement(textContent(), this);
+        document().setTitleElement(textContent(), this);
     return InsertionDone;
 }
 
@@ -52,14 +52,14 @@ void SVGTitleElement::removedFrom(ContainerNode* rootParent)
 {
     SVGElement::removedFrom(rootParent);
     if (rootParent->inDocument())
-        document()->removeTitle(this);
+        document().removeTitle(this);
 }
 
 void SVGTitleElement::childrenChanged(bool changedByParser, Node* beforeChange, Node* afterChange, int childCountDelta)
 {
     SVGElement::childrenChanged(changedByParser, beforeChange, afterChange, childCountDelta);
     if (inDocument())
-        document()->setTitleElement(textContent(), this);
+        document().setTitleElement(textContent(), this);
 }
 
 }