Update paint property subtrees on paint offset changes

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

Index: third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp b/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
index daad53c7bd927931e14cb6edae7f2f62659eb14a..dc65ccae69b4a1fd97fe66e7016d7fd23657e8a3 100644
--- a/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
@@ -921,6 +921,11 @@ void PaintPropertyTreeBuilder::updateContextForBoxPosition(
           -toLayoutBox(parentRow)->physicalLocation());
     }
   }
+
+  // Many paint properties depend on paint offset so we force an update of
+  // the entire subtree on paint offset changes.
+  if (object.previousPaintOffset() != context.current.paintOffset)
+    context.forceSubtreeUpdate = true;

[pdr., 2016/12/16 03:24:09]

This is the main change in this patch. Instead of using
object.setNeedsPaintPropertyUpdate(), we force the entire subtree to be updated.

 }
 
 void PaintPropertyTreeBuilder::updatePropertiesForSelf(