[LayoutNG] PODify NGLayoutInputNode and sub-classes.

third_party/WebKit/Source/core/layout/ng/layout_ng_block_flow.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef LayoutNGBlockFlow_h
 #define LayoutNGBlockFlow_h
 
 #include "core/CoreExport.h"
 #include "core/layout/LayoutBlockFlow.h"
 #include "core/layout/ng/inline/ng_inline_node_data.h"
 #include "core/layout/ng/ng_block_node.h"
 
 namespace blink {
 
 // This overrides the default layout block algorithm to use Layout NG.
 class CORE_EXPORT LayoutNGBlockFlow final : public LayoutBlockFlow {
  public:
   explicit LayoutNGBlockFlow(Element*);
   ~LayoutNGBlockFlow() override = default;
 
   void UpdateBlockLayout(bool relayout_children) override;
-  NGBlockNode* BoxForTesting() const { return box_.Get(); }
 
   const char* GetName() const override { return "LayoutNGBlockFlow"; }
 
   NGInlineNodeData& GetNGInlineNodeData() const;
   void ResetNGInlineNodeData();
+  bool HasNGInlineNodeData() const { return ng_inline_node_data_.get(); }
 
  private:
   bool IsOfType(LayoutObjectType) const override;
 
   std::unique_ptr<NGInlineNodeData> ng_inline_node_data_;
-  Persistent<NGBlockNode> box_;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutNGBlockFlow, IsLayoutNGBlockFlow());
 
 }  // namespace blink
 
 #endif  // LayoutNGBlockFlow_h