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

third_party/WebKit/Source/core/layout/api/LineLayoutBlockFlow.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 LineLayoutBlockFlow_h
 #define LineLayoutBlockFlow_h
 
 #include "core/layout/FloatingObjects.h"
 #include "core/layout/LayoutBlockFlow.h"
 #include "core/layout/api/LineLayoutBox.h"
@@ skipping 12 matching lines @@
         : LineLayoutBox(blockFlow)
     {
     }
 
     explicit LineLayoutBlockFlow(const LineLayoutItem& item)
         : LineLayoutBox(item)
     {
         ASSERT(!item || item.isLayoutBlockFlow());
     }
 
+    LineLayoutBlockFlow(std::nullptr_t) : LineLayoutBox(nullptr) { }
+
     LineLayoutBlockFlow() { }
 
     LineLayoutItem firstChild() const
     {
         return LineLayoutItem(toBlockFlow()->firstChild());
     }
     LineLayoutItem lastChild() const
     {
         return LineLayoutItem(toBlockFlow()->lastChild());
     }
@@ skipping 134 matching lines @@
     }
 
 private:
     LayoutBlockFlow* toBlockFlow() { return toLayoutBlockFlow(layoutObject()); };
     const LayoutBlockFlow* toBlockFlow() const { return toLayoutBlockFlow(layoutObject()); };
 };
 
 } // namespace blink
 
 #endif // LineLayoutBlockFlow_h