Recompute slow scroll regions after overflow recalc

Source/core/frame/FrameView.cpp

Index: Source/core/frame/FrameView.cpp
diff --git a/Source/core/frame/FrameView.cpp b/Source/core/frame/FrameView.cpp
index f6edc0fba69855013707d8c79d946afa76c46a7d..7cbf007227e5e0dc854315e0014c9b9302c9ffdf 100644
--- a/Source/core/frame/FrameView.cpp
+++ b/Source/core/frame/FrameView.cpp
@@ -643,6 +643,9 @@ void FrameView::recalcOverflowAfterStyleChange()
 
     layoutView->recalcOverflowAfterStyleChange();
 
+    if (ScrollingCoordinator* scrollingCoordinator = this->scrollingCoordinator())

[Rick Byers, 2015/08/05 15:04:05]

Please add a comment saying why this is the right place to hook (i.e. that
anything that updates overflow without causing layout also needs to update
non-fast scroll rects) - it's a bit of an implementation assumption that could
possibly change in the future I think.

[majidvp, 2015/08/05 15:39:35]

Acknowledged.

+        scrollingCoordinator->notifyOverflowUpdated();
+
     IntRect documentRect = layoutView->documentRect();
     if (scrollOrigin() == -documentRect.location() && contentsSize() == documentRect.size())
         return;