[Line Layout API] Convert AbstractInlineTextBox to new line layout API

third_party/WebKit/Source/core/layout/api/LineLayoutBox.h

 // Copyright 2015 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 LineLayoutBox_h
 #define LineLayoutBox_h
 
 #include "core/layout/LayoutBlockFlow.h"
 #include "core/layout/LayoutBox.h"
 #include "core/layout/api/LineLayoutBoxModel.h"
 #include "platform/LayoutUnit.h"
 
 namespace blink {
 
 class LayoutBox;
 
 class LineLayoutBox : public LineLayoutBoxModel {
 public:
     explicit LineLayoutBox(LayoutBox* layoutBox)
         : LineLayoutBoxModel(layoutBox)
     {
     }
 
     explicit LineLayoutBox(const LineLayoutItem& item)
         : LineLayoutBoxModel(item)
     {
         ASSERT(!item || item.isBox());
     }
 
+    LineLayoutBox(std::nullptr_t) : LineLayoutBoxModel(nullptr) { }
+
     LineLayoutBox() { }
 
     LayoutPoint location() const
     {
         return toBox()->location();
     }
 
     LayoutSize size() const
     {
         return toBox()->size();
@@ skipping 45 matching lines @@
 };
 
 inline LineLayoutBox LineLayoutItem::containingBlock() const
 {
     return LineLayoutBox(layoutObject()->containingBlock());
 }
 
 } // namespace blink
 
 #endif // LineLayoutBox_h