Support style invalidation for ::content.

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 102 matching lines @@
 void InsertionPoint::detach(const AttachContext& context)
 {
     for (size_t i = 0; i < m_distribution.size(); ++i)
         m_distribution.at(i)->lazyReattachIfAttached();
 
     HTMLElement::detach(context);
 }
 
 void InsertionPoint::willRecalcStyle(StyleRecalcChange change)
 {
-    if (change < Inherit)
+    if (change < Inherit && styleChangeType() < SubtreeStyleChange)

[chrishtr, 2014/10/16 02:02:51]

Is this part all that's needed to fix the attached bug?

[rune, 2014/10/16 07:23:32]

Yes. I started out to support invalidation for ::content, but found this bug on
the way. I can split it into two CLs.

         return;
     for (size_t i = 0; i < m_distribution.size(); ++i)
         m_distribution.at(i)->setNeedsStyleRecalc(SubtreeStyleChange, StyleChangeReasonForTracing::create(StyleChangeReason::PropagateInheritChangeToDistributedNodes));
 }
 
 bool InsertionPoint::shouldUseFallbackElements() const
 {
     return isActive() && !hasDistribution();
 }
 
@@ skipping 148 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 blink