Make the compositing assert disabler for paint invalidation more targeted.

Source/core/rendering/RenderLayerScrollableArea.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 385 matching lines @@
             && !layer()->hasNonCompositedChild()
             && !layer()->hasBlockSelectionGapBounds()
             && box().style()->backgroundLayers().attachment() != LocalBackgroundAttachment;
 
         if (usesCompositedScrolling() || onlyScrolledCompositedLayers)
             requiresPaintInvalidation = false;
     }
 
     // Just schedule a full paint invalidation of our object.
     if (requiresPaintInvalidation) {
+        // For querying RenderLayer::compositingState()
+        // This code appears correct, since scrolling outside of layout happens during activities that do not dirty compositing state.
+        DisableCompositingQueryAsserts disabler;
         if (box().frameView()->isInPerformLayout())
             box().setShouldDoFullPaintInvalidation(true);
         else
             box().invalidatePaintUsingContainer(paintInvalidationContainer, layer()->renderer()->previousPaintInvalidationRect(), InvalidationScroll);
     }
 
     // Schedule the scroll DOM event.
     if (box().node())
         box().node()->document().enqueueScrollEventForNode(box().node());
 
@@ skipping 1057 matching lines @@
 void RenderLayerScrollableArea::setTopmostScrollChild(RenderLayer* scrollChild)
 {
     // We only want to track the topmost scroll child for scrollable areas with
     // overlay scrollbars.
     if (!hasOverlayScrollbars())
         return;
     m_nextTopmostScrollChild = scrollChild;
 }
 
 } // namespace blink