WIP (Introduce WTF::NonNullPtr<T>.)

Source/core/dom/Attr.cpp

Index: Source/core/dom/Attr.cpp
diff --git a/Source/core/dom/Attr.cpp b/Source/core/dom/Attr.cpp
index 0d20c05a43f440b6aed7bf8616e12d0708ca5563..bd16d4e8cf1f598911620826c7d9a663c4966423 100644
--- a/Source/core/dom/Attr.cpp
+++ b/Source/core/dom/Attr.cpp
@@ -85,7 +85,7 @@ void Attr::createTextChild()
         // This does everything appendChild() would do in this situation (assuming m_ignoreChildrenChanged was set),
         // but much more efficiently.
         textNode->setParentOrShadowHostNode(this);
-        treeScope().adoptIfNeeded(textNode.get());
+        treeScope()->adoptIfNeeded(textNode.get());
         setFirstChild(textNode.get());
         setLastChild(textNode.get());
     }