Split StyleSurroundData::margin into four individual Lengths.

third_party/WebKit/Source/platform/LengthBox.h

 /*
     Copyright (C) 1999 Lars Knoll (knoll@kde.org)
     Copyright (C) 2006, 2008 Apple Inc. All rights reserved.
     Copyright (c) 2012, Google Inc. All rights reserved.
 
     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Library General Public
     License as published by the Free Software Foundation; either
     version 2 of the License, or (at your option) any later version.
 
@@ skipping 50 matching lines @@
                                     const Length& right,
                                     const Length& bottom);
   static const Length& Before(WritingMode,
                               const Length& top,
                               const Length& left,
                               const Length& right);
   static const Length& After(WritingMode,
                              const Length& bottom,
                              const Length& left,
                              const Length& right);
+  static const Length& Start(WritingMode,
+                             TextDirection,
+                             const Length& top,
+                             const Length& left,
+                             const Length& right,
+                             const Length& bottom);
+  static const Length& End(WritingMode,
+                           TextDirection,
+                           const Length& top,
+                           const Length& left,
+                           const Length& right,
+                           const Length& bottom);
+  static const Length& Over(WritingMode,
+                            const Length& top,
+                            const Length& right);
+  static const Length& Under(WritingMode,
+                             const Length& bottom,
+                             const Length& left);
 
   const Length& Left() const { return left_; }
   const Length& Right() const { return right_; }
   const Length& Top() const { return top_; }
   const Length& Bottom() const { return bottom_; }
 
   const Length& LogicalLeft(WritingMode) const;
   const Length& LogicalRight(WritingMode) const;
 
   const Length& Before(WritingMode) const;
@@ skipping 18 matching lines @@
   // Must be public for SET_VAR in ComputedStyle.h
   Length left_;
   Length right_;
   Length top_;
   Length bottom_;
 };
 
 }  // namespace blink
 
 #endif  // LengthBox_h