Mark when we may have been invalidated to early out on repaintTreeAfterLayout.

Source/core/rendering/RenderLayerScrollableArea.cpp

Index: Source/core/rendering/RenderLayerScrollableArea.cpp
diff --git a/Source/core/rendering/RenderLayerScrollableArea.cpp b/Source/core/rendering/RenderLayerScrollableArea.cpp
index a89c991de7871f0d964197188dea146590fa9c87..e0f5e29674670526e8f2efbd996997da337ba9b4 100644
--- a/Source/core/rendering/RenderLayerScrollableArea.cpp
+++ b/Source/core/rendering/RenderLayerScrollableArea.cpp
@@ -350,6 +350,8 @@ void RenderLayerScrollableArea::setScrollOffset(const IntPoint& newScrollOffset)
     if (scrollOffset() == toIntSize(newScrollOffset))
         return;
 
+    layer()->renderer()->setMayNeedInvalidation(true);
+
     setScrollOffset(toIntSize(newScrollOffset));
 
     LocalFrame* frame = box().frame();
@@ -590,6 +592,8 @@ void RenderLayerScrollableArea::updateAfterLayout()
     if (box().style()->appearance() == ListboxPart)
         return;
 
+    box().setMayNeedInvalidation(true);
+
     m_scrollDimensionsDirty = true;
     IntSize originalScrollOffset = adjustedScrollOffset();