Calculate paint invalidation rect for scrollbars

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

Index: third_party/WebKit/Source/core/layout/LayoutView.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutView.cpp b/third_party/WebKit/Source/core/layout/LayoutView.cpp
index 5313853971f78c318f8c62e23ac8dded92e9d190..18b2dbe696e4b951579933ee764331264a55a631 100644
--- a/third_party/WebKit/Source/core/layout/LayoutView.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutView.cpp
@@ -455,12 +455,14 @@ void LayoutView::mapRectToPaintInvalidationBacking(const LayoutBoxModelObject* p
         return;
 
     if (LayoutBox* obj = owner->layoutBox()) {
-        // Intersect the viewport with the paint invalidation rect.
-        LayoutRect viewRectangle = viewRect();
-        rect.intersect(viewRectangle);
+        if (!state || !state->viewClippingAndScrollOffsetDisabled()) {
+            // Intersect the viewport with the paint invalidation rect.
+            LayoutRect viewRectangle = viewRect();
+            rect.intersect(viewRectangle);
 
-        // Adjust for scroll offset of the view.
-        rect.moveBy(-viewRectangle.location());
+            // Adjust for scroll offset of the view.
+            rect.moveBy(-viewRectangle.location());
+        }
 
         // Adjust for frame border.
         rect.move(obj->contentBoxOffset());