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..48c61faf2c1c26fe62f8923b0f8834ff654f0677 100644
--- a/Source/core/frame/FrameView.cpp
+++ b/Source/core/frame/FrameView.cpp
@@ -643,6 +643,11 @@ void FrameView::recalcOverflowAfterStyleChange()
 
     layoutView->recalcOverflowAfterStyleChange();
 
+    // Changing overflow should notify scrolling coordinator to ensures that it
+    // updates non-fast scroll rects even if there is no layout.
+    if (ScrollingCoordinator* scrollingCoordinator = this->scrollingCoordinator())
+        scrollingCoordinator->notifyOverflowUpdated();
+
     IntRect documentRect = layoutView->documentRect();
     if (scrollOrigin() == -documentRect.location() && contentsSize() == documentRect.size())
         return;