Use scrollContentsSlowPath when scrolling with background-attachment: fixed

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 1236 matching lines @@
 void FrameView::scrollContentsIfNeeded()
 {
     bool didScroll = !pendingScrollDelta().isZero();
     ScrollView::scrollContentsIfNeeded();
     if (didScroll)
         updateFixedElementPaintInvalidationRectsAfterScroll();
 }
 
 bool FrameView::scrollContentsFastPath(const IntSize& scrollDelta, const IntRect& rectToScroll)
 {
-    if (!contentsInCompositedLayer())
+    if (!contentsInCompositedLayer() || hasSlowRepaintObjects())
         return false;
 
     if (!m_viewportConstrainedObjects || m_viewportConstrainedObjects->isEmpty()) {
         hostWindow()->scroll();
         return true;
     }
 
     // Get the rects of the fixed objects visible in the rectToScroll
     Region regionToUpdate;
     ViewportConstrainedObjectSet::const_iterator end = m_viewportConstrainedObjects->end();
@@ skipping 1864 matching lines @@
 void FrameView::willRemoveScrollbar(Scrollbar* scrollbar, ScrollbarOrientation orientation)
 {
     ScrollableArea::willRemoveScrollbar(scrollbar, orientation);
     if (AXObjectCache* cache = axObjectCache()) {
         cache->remove(scrollbar);
         cache->handleScrollbarUpdate(this);
     }
 }
 
 } // namespace blink