Introduce and use type casting functions for several HTMLCollection types

Source/core/html/HTMLAllCollection.cpp

Index: Source/core/html/HTMLAllCollection.cpp
diff --git a/Source/core/html/HTMLAllCollection.cpp b/Source/core/html/HTMLAllCollection.cpp
index 9e7bcd3d128f16274e96351851c706bdb257c129..38c620a350bca0ae1c8c60a1facb36581f56d86a 100644
--- a/Source/core/html/HTMLAllCollection.cpp
+++ b/Source/core/html/HTMLAllCollection.cpp
@@ -33,11 +33,12 @@ namespace WebCore {
 
 PassRefPtrWillBeRawPtr<HTMLAllCollection> HTMLAllCollection::create(ContainerNode& node, CollectionType type)
 {
-    return adoptRefWillBeNoop(new HTMLAllCollection(node, type));
+    ASSERT_UNUSED(type, type == DocAll);
+    return adoptRefWillBeNoop(new HTMLAllCollection(node));
 }
 
-HTMLAllCollection::HTMLAllCollection(ContainerNode& node, CollectionType type)
-    : HTMLCollection(node, type, DoesNotOverrideItemAfter)
+HTMLAllCollection::HTMLAllCollection(ContainerNode& node)
+    : HTMLCollection(node, DocAll, DoesNotOverrideItemAfter)
 {
     ScriptWrappable::init(this);
 }