Pass rootNode by reference when constructing node lists / collections

Source/core/html/LabelsNodeList.h

Index: Source/core/html/LabelsNodeList.h
diff --git a/Source/core/html/LabelsNodeList.h b/Source/core/html/LabelsNodeList.h
index 919edb1b0bbd5006c8f6d2c9d910819efd322aee..889425755e0bd714ac441d88af41a40f20ce5f3d 100644
--- a/Source/core/html/LabelsNodeList.h
+++ b/Source/core/html/LabelsNodeList.h
@@ -32,7 +32,7 @@ namespace WebCore {
 
 class LabelsNodeList FINAL : public LiveNodeList {
 public:
-    static PassRefPtr<LabelsNodeList> create(ContainerNode* ownerNode, CollectionType type)
+    static PassRefPtr<LabelsNodeList> create(ContainerNode& ownerNode, CollectionType type)
     {
         ASSERT_UNUSED(type, type == LabelsNodeListType);
         return adoptRef(new LabelsNodeList(ownerNode));
@@ -41,7 +41,7 @@ public:
     virtual ~LabelsNodeList();
 
 protected:
-    explicit LabelsNodeList(ContainerNode*);
+    explicit LabelsNodeList(ContainerNode&);
 
     virtual bool nodeMatches(const Element&) const OVERRIDE;
 };