Split StyleSurroundData::margin into four individual Lengths.

third_party/WebKit/Source/core/style/ComputedStyle.cpp

 /*
  * Copyright (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights
  * reserved.
  * Copyright (C) 2011 Adobe Systems Incorporated. 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 509 matching lines @@
 
   if ((!diff.NeedsFullLayout() || !diff.NeedsFullPaintInvalidation()) &&
       DiffNeedsFullLayoutAndPaintInvalidation(other)) {
     diff.SetNeedsFullLayout();
     diff.SetNeedsPaintInvalidationObject();
   }
 
   if (!diff.NeedsFullLayout() && DiffNeedsFullLayout(other))
     diff.SetNeedsFullLayout();
 
-  if (!diff.NeedsFullLayout() && Margin() != other.Margin()) {
+  if (!diff.NeedsFullLayout() && !MarginEqual(other)) {
     // Relative-positioned elements collapse their margins so need a full
     // layout.
     if (HasOutOfFlowPosition())
       diff.SetNeedsPositionedMovementLayout();
     else
       diff.SetNeedsFullLayout();
   }
 
   if (!diff.NeedsFullLayout() && GetPosition() != EPosition::kStatic &&
       !OffsetEqual(other)) {
@@ skipping 41 matching lines @@
     if (box_->Width() != other.box_->Width() ||
         box_->MinWidth() != other.box_->MinWidth() ||
         box_->MaxWidth() != other.box_->MaxWidth() ||
         box_->Height() != other.box_->Height() ||
         box_->MinHeight() != other.box_->MinHeight() ||
         box_->MaxHeight() != other.box_->MaxHeight())
       return true;
   }
 
   if (surround_.Get() != other.surround_.Get()) {
-    if (Margin() != other.Margin() || !OffsetEqual(other) ||
+    if (!MarginEqual(other) || !OffsetEqual(other) ||
         Padding() != other.Padding())
       return true;
   }
 
   if (diff.TransformChanged())
     return true;
 
   return false;
 }
 
@@ skipping 1900 matching lines @@
     if (value < 0)
       fvalue -= 0.5f;
     else
       fvalue += 0.5f;
   }
 
   return RoundForImpreciseConversion<int>(fvalue / zoom_factor);
 }
 
 }  // namespace blink