Fix several corner case issues of scrollbar paint invalidation

third_party/WebKit/Source/core/layout/LayoutBox.cpp

Index: third_party/WebKit/Source/core/layout/LayoutBox.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutBox.cpp b/third_party/WebKit/Source/core/layout/LayoutBox.cpp
index 4a51e697ace3d6acff949ed32c58217422ca0800..832259d9c042658ed6f4d5ca8801032e9cd22fa4 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBox.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBox.cpp
@@ -4845,4 +4845,11 @@ ShapeOutsideInfo* LayoutBox::shapeOutsideInfo() const
     return ShapeOutsideInfo::isEnabledFor(*this) ? ShapeOutsideInfo::info(*this) : nullptr;
 }
 
+void LayoutBox::clearPreviousPaintInvalidationRects()
+{
+    LayoutBoxModelObject::clearPreviousPaintInvalidationRects();
+    if (PaintLayerScrollableArea* scrollableArea = this->scrollableArea())
+        scrollableArea->clearPreviousPaintInvalidationRects();
+}
+
 } // namespace blink