SubtreeStyleChange will propagate through <content>.

third_party/WebKit/Source/core/css/invalidation/StyleSheetInvalidationAnalysis.cpp

 /*
  * Copyright (C) 2012 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 57 matching lines @@
             return false;
         ASSERT(scopeSelector->match() == CSSSelector::Class || scopeSelector->match() == CSSSelector::Id);
         if (scopeSelector->match() == CSSSelector::Id)
             idScopes.add(scopeSelector->value().impl());
         else
             classScopes.add(scopeSelector->value().impl());
     }
     return true;
 }
 
-static bool hasDistributedRule(StyleSheetContents* styleSheetContents)
-{
-    const WillBeHeapVector<RefPtrWillBeMember<StyleRuleBase>>& rules = styleSheetContents->childRules();
-    for (unsigned i = 0; i < rules.size(); i++) {
-        const StyleRuleBase* rule = rules[i].get();
-        if (!rule->isStyleRule())
-            continue;
-
-        const StyleRule* styleRule = toStyleRule(rule);
-        const CSSSelectorList& selectorList = styleRule->selectorList();
-        for (size_t selectorIndex = 0; selectorIndex != kNotFound; selectorIndex = selectorList.indexOfNextSelectorAfter(selectorIndex)) {
-            if (selectorList.hasShadowDistributedAt(selectorIndex))
-                return true;
-        }
-    }
-    return false;
-}
-
 static bool ruleAdditionMightRequireDocumentStyleRecalc(StyleRuleBase* rule)
 {
     // This funciton is conservative. We only return false when we know that
     // the added @rule can't require style recalcs.
     switch (rule->type()) {
     case StyleRule::Import: // Whatever we import should do its own analysis, we don't need to invalidate the document here!
     case StyleRule::Page: // Page rules apply only during printing, we force a full-recalc before printing.
         return false;
 
     case StyleRule::Media: // If the media rule doesn't apply, we could avoid recalc.
@@ skipping 26 matching lines @@
     // Then test if we actually have any of those in the tree at the moment.
     const WillBeHeapVector<RefPtrWillBeMember<StyleRuleImport>>& importRules = styleSheetContents->importRules();
     for (unsigned i = 0; i < importRules.size(); ++i) {
         if (!importRules[i]->styleSheet())
             continue;
         analyzeStyleSheet(importRules[i]->styleSheet());
         if (m_dirtiesAllStyle)
             return;
     }
 
-    if (m_treeScope->rootNode().isShadowRoot()) {
-        if (hasDistributedRule(styleSheetContents))
-            m_hasDistributedRules = true;
+    if (m_treeScope->rootNode().isShadowRoot())
         return;
-    }
 
     const WillBeHeapVector<RefPtrWillBeMember<StyleRuleBase>>& rules = styleSheetContents->childRules();
     for (unsigned i = 0; i < rules.size(); i++) {
         StyleRuleBase* rule = rules[i].get();
         if (!rule->isStyleRule()) {
             if (ruleAdditionMightRequireDocumentStyleRecalc(rule)) {
                 m_dirtiesAllStyle = true;
                 return;
             }
             continue;
@@ skipping 13 matching lines @@
     if (classScopes.isEmpty() || !element->hasClass())
         return false;
     const SpaceSplitString& classNames = element->classNames();
     for (unsigned i = 0; i < classNames.size(); ++i) {
         if (classScopes.contains(classNames[i].impl()))
             return true;
     }
     return false;
 }
 
-static ContainerNode* outermostShadowHost(ContainerNode& host)
-{
-    ContainerNode* outerHost = &host;
-    while (outerHost->isInShadowTree())
-        outerHost = outerHost->containingShadowRoot()->host();
-    return outerHost;
-}
-
 void StyleSheetInvalidationAnalysis::invalidateStyle()
 {
     ASSERT(!m_dirtiesAllStyle);
 
     if (m_treeScope->rootNode().isShadowRoot()) {
-        ContainerNode* invalidationRoot = toShadowRoot(m_treeScope->rootNode()).host();
-        if (m_hasDistributedRules)
-            invalidationRoot = outermostShadowHost(*invalidationRoot);
-        invalidationRoot->setNeedsStyleRecalc(SubtreeStyleChange, StyleChangeReasonForTracing::create(StyleChangeReason::StyleSheetChange));
+        ContainerNode* shadowHost = toShadowRoot(m_treeScope->rootNode()).host();
+        shadowHost->setNeedsStyleRecalc(SubtreeStyleChange, StyleChangeReasonForTracing::create(StyleChangeReason::StyleSheetChange));
         return;
     }
 
     if (m_idScopes.isEmpty() && m_classScopes.isEmpty())
         return;
     Element* element = ElementTraversal::firstWithin(m_treeScope->document());
     while (element) {
         if (elementMatchesSelectorScopes(element, m_idScopes, m_classScopes)) {
             element->setNeedsStyleRecalc(SubtreeStyleChange, StyleChangeReasonForTracing::create(StyleChangeReason::StyleSheetChange));
             // The whole subtree is now invalidated, we can skip to the next sibling.
             element = ElementTraversal::nextSkippingChildren(*element);
             continue;
         }
         element = ElementTraversal::next(*element);
     }
 }
 
 }