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

Source/core/css/resolver/ScopedStyleResolver.cpp

Index: Source/core/css/resolver/ScopedStyleResolver.cpp
diff --git a/Source/core/css/resolver/ScopedStyleResolver.cpp b/Source/core/css/resolver/ScopedStyleResolver.cpp
index cb60fdc2797d8951a99328e1a12bb8ff11abd8cb..9185a08d775206fe1b185e13bcdf99f1e7bfbdaa 100644
--- a/Source/core/css/resolver/ScopedStyleResolver.cpp
+++ b/Source/core/css/resolver/ScopedStyleResolver.cpp
@@ -142,11 +142,11 @@ void ScopedStyleTree::collectScopedResolversForHostedShadowTrees(const Element*
 void ScopedStyleTree::resolveScopedKeyframesRules(const Element* element, Vector<ScopedStyleResolver*, 8>& resolvers)
 {
     Document& document = element->document();
-    TreeScope& treeScope = element->treeScope();
-    bool applyAuthorStyles = treeScope.applyAuthorStyles();
+    NonNullPtr<TreeScope> treeScope = element->treeScope();
+    bool applyAuthorStyles = treeScope->applyAuthorStyles();
 
     for (ScopedStyleResolver* scopedResolver = scopedResolverFor(element); scopedResolver; scopedResolver = scopedResolver->parent()) {
-        if (&scopedResolver->treeScope() == &treeScope || (applyAuthorStyles && &scopedResolver->treeScope() == &document))
+        if (scopedResolver->treeScope() == treeScope || (applyAuthorStyles && scopedResolver->treeScope() == &document))
             resolvers.append(scopedResolver);
     }
 }