Fix AXScrollbar from being recreated right after removal

Source/core/frame/FrameView.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Dirk Mueller <mueller@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
@@ skipping 3002 matching lines @@
 void FrameView::didAddScrollbar(Scrollbar* scrollbar, ScrollbarOrientation orientation)
 {
     ScrollableArea::didAddScrollbar(scrollbar, orientation);
     if (AXObjectCache* cache = axObjectCache())
         cache->handleScrollbarUpdate(this);
 }
 
 void FrameView::willRemoveScrollbar(Scrollbar* scrollbar, ScrollbarOrientation orientation)
 {
     ScrollableArea::willRemoveScrollbar(scrollbar, orientation);
-    if (AXObjectCache* cache = axObjectCache()) {
+    if (AXObjectCache* cache = axObjectCache())
         cache->remove(scrollbar);
-        cache->handleScrollbarUpdate(this);
-    }
 }
 
 void FrameView::setTopControlsViewportAdjustment(float adjustment)
 {
     m_topControlsViewportAdjustment = adjustment;
 }
 
 IntPoint FrameView::maximumScrollPosition() const
 {
     // Make the same calculation as in CC's LayerImpl::MaxScrollOffset()
@@ skipping 30 matching lines @@
         didAddScrollbar(m_horizontalScrollbar.get(), HorizontalScrollbar);
         m_horizontalScrollbar->styleChanged();
     } else {
         willRemoveScrollbar(m_horizontalScrollbar.get(), HorizontalScrollbar);
         // If the scrollbar has been marked as overlapping the window resizer,
         // then its removal should reduce the count.
         if (m_horizontalScrollbar->overlapsResizer())
             adjustScrollbarsAvoidingResizerCount(-1);
         removeChild(m_horizontalScrollbar.get());
         m_horizontalScrollbar = nullptr;
+        if (AXObjectCache* cache = axObjectCache())
+            cache->handleScrollbarUpdate(this);
     }
 
     if (RuntimeEnabledFeatures::slimmingPaintEnabled())
         invalidateScrollCorner(scrollCornerRect());
 }
 
 void FrameView::setHasVerticalScrollbar(bool hasBar)
 {
     if (hasBar == !!m_verticalScrollbar)
         return;
 
     if (hasBar) {
         m_verticalScrollbar = createScrollbar(VerticalScrollbar);
         addChild(m_verticalScrollbar.get());
         didAddScrollbar(m_verticalScrollbar.get(), VerticalScrollbar);
         m_verticalScrollbar->styleChanged();
     } else {
         willRemoveScrollbar(m_verticalScrollbar.get(), VerticalScrollbar);
         // If the scrollbar has been marked as overlapping the window resizer,
         // then its removal should reduce the count.
         if (m_verticalScrollbar->overlapsResizer())
             adjustScrollbarsAvoidingResizerCount(-1);
         removeChild(m_verticalScrollbar.get());
         m_verticalScrollbar = nullptr;
+        if (AXObjectCache* cache = axObjectCache())
+            cache->handleScrollbarUpdate(this);
     }
 
     if (RuntimeEnabledFeatures::slimmingPaintEnabled())
         invalidateScrollCorner(scrollCornerRect());
 }
 
 void FrameView::setScrollbarModes(ScrollbarMode horizontalMode, ScrollbarMode verticalMode,
     bool horizontalLock, bool verticalLock)
 {
     bool needsUpdate = false;
@@ skipping 895 matching lines @@
 
     if (!graphicsLayer)
         return;
 
     DeprecatedPaintLayer::mapRectToPaintInvalidationBacking(localFrame->contentLayoutObject(), paintInvalidationContainer, viewRect);
 
     graphicsLayerTimingRequests.add(graphicsLayer, Vector<std::pair<int64_t, WebRect>>()).storedValue->value.append(std::make_pair(m_frame->frameID(), enclosingIntRect(viewRect)));
 }
 
 } // namespace blink