Optimize scroll adjustment for paint invalidation

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

Index: third_party/WebKit/Source/core/paint/ObjectPaintInvalidator.cpp
diff --git a/third_party/WebKit/Source/core/paint/ObjectPaintInvalidator.cpp b/third_party/WebKit/Source/core/paint/ObjectPaintInvalidator.cpp
index 256b397caaf59cb537cd978413d18291e05fb323..d3960945ef8f0c985ecf88ca0e4ec765a1dd2829 100644
--- a/third_party/WebKit/Source/core/paint/ObjectPaintInvalidator.cpp
+++ b/third_party/WebKit/Source/core/paint/ObjectPaintInvalidator.cpp
@@ -405,8 +405,10 @@ LayoutRect ObjectPaintInvalidator::invalidatePaintRectangle(
   LayoutRect dirtyRectOnBacking = dirtyRect;
   PaintLayer::mapRectToPaintInvalidationBacking(
       m_object, paintInvalidationContainer, dirtyRectOnBacking);
-  dirtyRectOnBacking.move(m_object.scrollAdjustmentForPaintInvalidation(
-      paintInvalidationContainer));
+  if (m_object != paintInvalidationContainer) {
+    dirtyRectOnBacking.move(
+        paintInvalidationContainer.scrollAdjustmentForPaintInvalidation());
+  }
   invalidatePaintUsingContainer(paintInvalidationContainer, dirtyRectOnBacking,
                                 PaintInvalidationRectangle);