Revert of Separate repaint and layout requirements of StyleDifference (Step 1)

Source/core/rendering/style/RenderStyleConstants.h

Index: Source/core/rendering/style/RenderStyleConstants.h
diff --git a/Source/core/rendering/style/RenderStyleConstants.h b/Source/core/rendering/style/RenderStyleConstants.h
index 002ebc498bed2b09b703116ea2bc3cd5d8f6bded..f9f384ab49f23b7c4f823b60e542066b54985e9a 100644
--- a/Source/core/rendering/style/RenderStyleConstants.h
+++ b/Source/core/rendering/style/RenderStyleConstants.h
@@ -44,7 +44,6 @@ enum PrintColorAdjust {
     PrintColorAdjustExact
 };
 
-// FIXME: To be replaced by StyleDifference defined in StyleDifference.h.
 // The difference between two styles.  The following values are used:
 // - StyleDifferenceEqual - The two styles are identical.
 //   FIXME: When style difference is context sensitive, RenderStyle::visualInvalidationDiff() may return
@@ -54,7 +53,7 @@ enum PrintColorAdjust {
 // - StyleDifferenceRepaintLayer - The layer and its descendant layers need to be repainted.
 // - StyleDifferenceLayoutPositionedMovementOnly - Only the position of this positioned object has been updated.
 // - StyleDifferenceLayout - A full layout is required.
-enum StyleDifferenceLegacy {
+enum StyleDifference {
     StyleDifferenceEqual,
     StyleDifferenceRecompositeLayer,
     StyleDifferenceRepaint,