Always invalidate sticky constraints on the ancestor overflow layer

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2005, 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 406 matching lines @@
     if (newStyleIsViewportConstained != oldStyleIsViewportConstrained) {
       if (newStyleIsViewportConstained && layer())
         frameView->addViewportConstrainedObject(this);
       else
         frameView->removeViewportConstrainedObject(this);
     }
   }
 }
 
 void LayoutBoxModelObject::invalidateStickyConstraints() {
-  if (!layer())
-    return;
+  PaintLayer* enclosing = enclosingLayer();
+
+  if (PaintLayerScrollableArea* scrollableArea =
+          enclosing->getScrollableArea()) {
+    scrollableArea->invalidateAllStickyConstraints();
+    // If this object doesn't have a layer and its enclosing layer is a scroller
+    // then we don't need to invalidate the sticky constraints on the ancestor
+    // scroller because the enclosing scroller won't have changed size.
+    if (!layer())
+      return;
+  }
 
   // This intentionally uses the stale ancestor overflow layer compositing input
   // as if we have saved constraints for this layer they were saved in the
   // previous frame.
   DisableCompositingQueryAsserts disabler;
   if (const PaintLayer* ancestorOverflowLayer =
-          layer()->ancestorOverflowLayer())
+          enclosing->ancestorOverflowLayer())
     ancestorOverflowLayer->getScrollableArea()
         ->invalidateAllStickyConstraints();
 }
 
 void LayoutBoxModelObject::createLayer() {
   ASSERT(!m_layer);
   m_layer = WTF::makeUnique<PaintLayer>(this);
   setHasLayer(true);
   m_layer->insertOnlyThisLayerAfterStyleChange();
 }
@@ skipping 901 matching lines @@
   if (rootElementStyle->hasBackground())
     return false;
 
   if (node() != document().firstBodyElement())
     return false;
 
   return true;
 }
 
 }  // namespace blink