Split StyleSurroundData::margin into four individual Lengths.

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

Index: third_party/WebKit/Source/core/style/ComputedStyle.cpp
diff --git a/third_party/WebKit/Source/core/style/ComputedStyle.cpp b/third_party/WebKit/Source/core/style/ComputedStyle.cpp
index 96c46e96e43b1d6ad9a8004e7bf0447ba7020a9f..10ae30fe8df0ea58d7adbbbd99078c68bca03848 100644
--- a/third_party/WebKit/Source/core/style/ComputedStyle.cpp
+++ b/third_party/WebKit/Source/core/style/ComputedStyle.cpp
@@ -527,7 +527,7 @@ StyleDifference ComputedStyle::VisualInvalidationDiff(
   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())
@@ -589,7 +589,7 @@ bool ComputedStyle::ScrollAnchorDisablingPropertyChanged(
   }
 
   if (surround_.Get() != other.surround_.Get()) {
-    if (Margin() != other.Margin() || !OffsetEqual(other) ||
+    if (!MarginEqual(other) || !OffsetEqual(other) ||
         Padding() != other.Padding())
       return true;
   }