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

Source/core/dom/TreeScopeAdopter.h

Index: Source/core/dom/TreeScopeAdopter.h
diff --git a/Source/core/dom/TreeScopeAdopter.h b/Source/core/dom/TreeScopeAdopter.h
index 4ad97606d5e3cc44dae37face1c709255b5e2efe..0d8569e14193f0ed438f66988762508a52f773ec 100644
--- a/Source/core/dom/TreeScopeAdopter.h
+++ b/Source/core/dom/TreeScopeAdopter.h
@@ -55,11 +55,11 @@ private:
     TreeScope* m_oldScope;
 };
 
-// FIXME: Should take |TreeScope&| instead of |TreeScope*|.
+// FIXME: Should take |NonNullPtr<TreeScope>| instead of |TreeScope*|.
 inline TreeScopeAdopter::TreeScopeAdopter(Node* toAdopt, TreeScope* newScope)
     : m_toAdopt(toAdopt)
     , m_newScope(newScope)
-    , m_oldScope(&toAdopt->treeScope())
+    , m_oldScope(toAdopt->treeScope().get())
 {
     ASSERT(newScope);
 }