Remove DEFINE_TYPE_CASTS from blink::EmptyNodeList

This CL removes old downcast helpers generated by macro
DEFINE_TYPE_CASTS.The primary goal of this CL is to use new downcast
helpers implemented using C++11 type traits.

Bug: 891908
Change-Id: Ib00118d7419f371124317376076772ef81d41580
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1906613
Commit-Queue: Abhijeet Kandalkar <abhijeet@igalia.com>
Reviewed-by: Christian Biesinger <cbiesinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#714158}

third_party/blink/renderer/core/dom/empty_node_list.h

@@ -33,6 +33,7 @@
 #define THIRD_PARTY_BLINK_RENDERER_CORE_DOM_EMPTY_NODE_LIST_H_
 
 #include "third_party/blink/renderer/core/dom/node_list.h"
+#include "third_party/blink/renderer/platform/wtf/casting.h"
 
 namespace blink {
 
@@ -55,11 +56,15 @@ class EmptyNodeList final : public NodeList {
   Member<Node> owner_;
 };
 
-DEFINE_TYPE_CASTS(EmptyNodeList,
-                  NodeList,
-                  nodeList,
-                  nodeList->IsEmptyNodeList(),
-                  nodeList.IsEmptyNodeList());
+template <>
+struct DowncastTraits<EmptyNodeList> {
+  static bool AllowFrom(const NodeList& nodeList) {
+    return nodeList.IsEmptyNodeList();
+  }
+  static bool AllowFrom(const NodeList* nodeList) {
+    return nodeList->IsEmptyNodeList();
+  }
+};
 
 }  // namespace blink
 

third_party/blink/renderer/core/dom/node_lists_node_data.h

@@ -54,7 +54,7 @@ class NodeListsNodeData final : public GarbageCollected<NodeListsNodeData> {
   EmptyNodeList* EnsureEmptyChildNodeList(Node& node) {
     DCHECK(ThreadState::Current()->IsGCForbidden());
     if (child_node_list_)
-      return ToEmptyNodeList(child_node_list_);
+      return To<EmptyNodeList>(child_node_list_.Get());
     auto* list = MakeGarbageCollected<EmptyNodeList>(node);
     child_node_list_ = list;
     return list;