[layoutng] Move and rename NGBoxMargins to NGBoxStrut

third_party/WebKit/Source/core/layout/ng/ng_margin_strut.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 NGMarginStrut_h
 #define NGMarginStrut_h
 
 #include "core/CoreExport.h"
 #include "platform/LayoutUnit.h"
 
 namespace blink {
 
-// Stores the four margins of a box
-struct NGBoxMargins {
-  LayoutUnit inline_start;
-  LayoutUnit inline_end;
-  LayoutUnit block_start;
-  LayoutUnit block_end;
-
-  LayoutUnit InlineSum() const { return inline_start + inline_end; }
-  LayoutUnit BlockSum() const { return block_start + block_end; }
-};
-
 // This struct is used for the margin collapsing calculation.
 struct NGMarginStrut {
   LayoutUnit margin_block_start;
   LayoutUnit margin_block_end;
 
   LayoutUnit negative_margin_block_start;
   LayoutUnit negative_margin_block_end;
 };
 
 }  // namespace blink
 
 #endif  // NGMarginStrut_h