Pass rootNode by reference when constructing node lists / collections

Source/core/dom/ClassCollection.h

Index: Source/core/dom/ClassCollection.h
diff --git a/Source/core/dom/ClassCollection.h b/Source/core/dom/ClassCollection.h
index a906537e0390c11c608d219bfb46e4ab8e59fdde..257cbb3b837b2d151d8eedf559cdf9c269254401 100644
--- a/Source/core/dom/ClassCollection.h
+++ b/Source/core/dom/ClassCollection.h
@@ -40,7 +40,7 @@ class ClassCollection FINAL : public HTMLCollection {
 public:
     // classNames argument is an AtomicString because it is common for Elements to share the same class names.
     // It is also used to construct a SpaceSplitString (m_classNames) and its constructor requires an AtomicString.
-    static PassRefPtr<ClassCollection> create(ContainerNode* rootNode, CollectionType type, const AtomicString& classNames)
+    static PassRefPtr<ClassCollection> create(ContainerNode& rootNode, CollectionType type, const AtomicString& classNames)
     {
         ASSERT_UNUSED(type, type == ClassCollectionType);
         return adoptRef(new ClassCollection(rootNode, classNames));
@@ -51,7 +51,7 @@ public:
     bool elementMatches(const Element&) const;
 
 private:
-    ClassCollection(ContainerNode* rootNode, const AtomicString& classNames);
+    ClassCollection(ContainerNode& rootNode, const AtomicString& classNames);
 
     SpaceSplitString m_classNames;
     AtomicString m_originalClassNames;