Compute style-determined compositing reasons during recalc style

Source/core/rendering/RenderLayer.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 1167 matching lines @@
 {
     const RenderLayer* curr = (includeSelf == IncludeSelf) ? this : parent();
     for (; curr; curr = curr->parent()) {
         if (curr->requiresFullLayerImageForFilters())
             return const_cast<RenderLayer*>(curr);
     }
 
     return 0;
 }
 
-void RenderLayer::setCompositingReasons(CompositingReasons reasons)
+void RenderLayer::setCompositingReasons(CompositingReasons reasons, CompositingReasons mask)
 {
-    if (m_compositingProperties.compositingReasons == reasons)
+    ASSERT(reasons == (reasons & mask));
+    if ((m_compositingProperties.compositingReasons & mask) == (reasons & mask))
         return;
-    m_compositingProperties.compositingReasons = reasons;
+    m_compositingProperties.compositingReasons = (reasons & mask) | (m_compositingProperties.compositingReasons & ~mask);
     m_clipper.setCompositingClipRectsDirty();
 }
 
 bool RenderLayer::hasAncestorWithFilterOutsets() const
 {
     for (const RenderLayer* curr = this; curr; curr = curr->parent()) {
         RenderLayerModelObject* renderer = curr->renderer();
         if (renderer->style()->hasFilterOutsets())
             return true;
     }
@@ skipping 2698 matching lines @@
     bool didPaintWithFilters = false;
 
     {
         // https://code.google.com/p/chromium/issues/detail?id=343759
         DisableCompositingQueryAsserts disabler;
         if (paintsWithFilters())
             didPaintWithFilters = true;
         updateFilters(oldStyle, renderer()->style());
     }
 
+    compositor()->updateStyleDeterminedCompositingReasons(this);
+
     // FIXME: Remove incremental compositing updates after fixing the chicken/egg issues
     // https://code.google.com/p/chromium/issues/detail?id=343756
     DisableCompositingQueryAsserts disabler;
 
     if (RenderLayer* compositingLayer = enclosingCompositingLayer())
         compositingLayer->compositedLayerMapping()->setNeedsGeometryUpdate();
 
     const RenderStyle* newStyle = renderer()->style();
 
     compositor()->updateLayerCompositingState(this, RenderLayerCompositor::UseChickenEggHacks);
@@ skipping 158 matching lines @@
     }
 }
 
 void showLayerTree(const WebCore::RenderObject* renderer)
 {
     if (!renderer)
         return;
     showLayerTree(renderer->enclosingLayer());
 }
 #endif