Fix under-invalidation of multicol with rule

third_party/WebKit/Source/core/paint/BoxPaintInvalidator.cpp

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/paint/BoxPaintInvalidator.h"
 
 #include "core/frame/Settings.h"
 #include "core/layout/LayoutView.h"
 #include "core/layout/compositing/CompositedLayerMapping.h"
 #include "core/paint/ObjectPaintInvalidator.h"
@@ skipping 144 matching lines @@
       m_box.mustInvalidateBackgroundOrBorderPaintOnWidthChange())
     return PaintInvalidationBorderBoxChange;
   if (oldBorderBoxSize.height() != newBorderBoxSize.height() &&
       m_box.mustInvalidateBackgroundOrBorderPaintOnHeightChange())
     return PaintInvalidationBorderBoxChange;
 
   // Needs to repaint frame boundaries.
   if (m_box.isFrameSet())
     return PaintInvalidationBorderBoxChange;
 
+  // Needs to repaint column rules.
+  if (m_box.isLayoutMultiColumnSet())
+    return PaintInvalidationBorderBoxChange;
+
   return PaintInvalidationIncremental;
 }
 
 bool BoxPaintInvalidator::backgroundGeometryDependsOnLayoutOverflowRect() {
   return !m_box.isDocumentElement() && !m_box.backgroundStolenForBeingBody() &&
          m_box.styleRef()
              .backgroundLayers()
              .thisOrNextLayersHaveLocalAttachment();
 }
 
@@ skipping 200 matching lines @@
 
 LayoutRect BoxPaintInvalidator::previousLayoutOverflowRect() {
   DCHECK(m_box.hasPreviousBoxGeometries() ==
          previousBoxGeometriesMap().contains(&m_box));
   return m_box.hasPreviousBoxGeometries()
              ? previousBoxGeometriesMap().get(&m_box).layoutOverflowRect
              : LayoutRect();
 }
 
 }  // namespace blink