:host-context selectors may affect insertion point descendants.

Source/core/dom/shadow/InsertionPoint.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 104 matching lines @@
         m_distribution.at(i)->lazyReattachIfAttached();
 
     HTMLElement::detach(context);
 }
 
 void InsertionPoint::willRecalcStyle(StyleRecalcChange change)
 {
     if (change < Inherit)
         return;
     for (size_t i = 0; i < m_distribution.size(); ++i)
-        m_distribution.at(i)->setNeedsStyleRecalc(LocalStyleChange);
+        m_distribution.at(i)->setNeedsStyleRecalc(SubtreeStyleChange);
 }
 
 bool InsertionPoint::shouldUseFallbackElements() const
 {
     return isActive() && !hasDistribution();
 }
 
 bool InsertionPoint::canBeActive() const
 {
     if (!isInShadowTree())
@@ skipping 149 matching lines @@
         if (!insertionPoints)
             return;
         for (size_t i = 0; i < insertionPoints->size(); ++i)
             results.append(insertionPoints->at(i).get());
         ASSERT(current != insertionPoints->last().get());
         current = insertionPoints->last().get();
     }
 }
 
 } // namespace WebCore