Reland of Fix slow repaint object registration

Source/core/layout/LayoutBox.h

Index: Source/core/layout/LayoutBox.h
diff --git a/Source/core/layout/LayoutBox.h b/Source/core/layout/LayoutBox.h
index aac6a3a51444f8ac93d4bc38685af30e1b1744e9..13c1424398702924f024c2444f4ae6e23dba2968 100644
--- a/Source/core/layout/LayoutBox.h
+++ b/Source/core/layout/LayoutBox.h
@@ -833,6 +833,8 @@
     // Returns true if the box intersects the viewport visible to the user.
     bool intersectsVisibleViewport();
 
+    void updateSlowRepaintStatusAfterStyleChange();
+
     // The width/height of the contents + borders + padding.  The x/y location is relative to our container (which is not always our parent).
     LayoutRect m_frameRect;