[repaint-after-layout] Skip full repaint if the style difference is layout.

Source/core/rendering/RenderBox.cpp

Index: Source/core/rendering/RenderBox.cpp
diff --git a/Source/core/rendering/RenderBox.cpp b/Source/core/rendering/RenderBox.cpp
index d3b5e1fbda84ec716b46b55258130dfe6e50614f..a236c9ada01d843e53929ccaf2f2705367cd6fed 100644
--- a/Source/core/rendering/RenderBox.cpp
+++ b/Source/core/rendering/RenderBox.cpp
@@ -145,7 +145,9 @@ void RenderBox::styleWillChange(StyleDifference diff, const RenderStyle* newStyl
         // the canvas.  Just dirty the entire canvas when our style changes substantially.
         if (diff >= StyleDifferenceRepaint && node() &&
             (isHTMLHtmlElement(*node()) || isHTMLBodyElement(*node()))) {
-            view()->repaint();
+
+            if (!RuntimeEnabledFeatures::repaintAfterLayoutEnabled() || diff != StyleDifferenceLayout)
+                view()->repaint();
 
             if (oldStyle->hasEntirelyFixedBackground() != newStyle->hasEntirelyFixedBackground())
                 view()->compositor()->rootFixedBackgroundsChanged();