Only allow one shadowRoot.

sky/engine/core/dom/TreeScope.cpp

 /*
  * Copyright (C) 2011 Google Inc. All Rights Reserved.
  * 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
@@ skipping 74 matching lines @@
     if (m_selection) {
         m_selection->clearTreeScope();
         m_selection = nullptr;
     }
 
     if (m_parentTreeScope)
         m_parentTreeScope->guardDeref();
 #endif
 }
 
-TreeScope* TreeScope::olderShadowRootOrParentTreeScope() const
-{
-    if (rootNode().isShadowRoot()) {
-        if (ShadowRoot* olderShadowRoot = toShadowRoot(rootNode()).olderShadowRoot())
-            return olderShadowRoot;
-    }
-    return parentTreeScope();
-}
-
 bool TreeScope::isInclusiveOlderSiblingShadowRootOrAncestorTreeScopeOf(const TreeScope& scope) const
 {
-    for (const TreeScope* current = &scope; current; current = current->olderShadowRootOrParentTreeScope()) {
+    for (const TreeScope* current = &scope; current; current = current->parentTreeScope()) {
         if (current == this)
             return true;
     }
     return false;
 }
 
 bool TreeScope::rootNodeHasTreeSharedParent() const
 {
     return rootNode().hasTreeSharedParent();
 }
@@ skipping 179 matching lines @@
 
     for (unsigned i = std::min(index1, index2); i; --i) {
         const TreeScope* child1 = chain1[--index1];
         const TreeScope* child2 = chain2[--index2];
         if (child1 != child2) {
             Node* shadowHost1 = child1->rootNode().parentOrShadowHostNode();
             Node* shadowHost2 = child2->rootNode().parentOrShadowHostNode();
             if (shadowHost1 != shadowHost2)
                 return shadowHost1->compareDocumentPosition(shadowHost2, Node::TreatShadowTreesAsDisconnected);
 
-            for (const ShadowRoot* child = toShadowRoot(child2->rootNode()).olderShadowRoot(); child; child = child->olderShadowRoot())
-                if (child == child1)
-                    return Node::DOCUMENT_POSITION_FOLLOWING;
-
             return Node::DOCUMENT_POSITION_PRECEDING;
         }
     }
 
     // There was no difference between the two parent chains, i.e., one was a subset of the other. The shorter
     // chain is the ancestor.
     return index1 < index2 ?
         Node::DOCUMENT_POSITION_FOLLOWING | Node::DOCUMENT_POSITION_CONTAINED_BY :
         Node::DOCUMENT_POSITION_PRECEDING | Node::DOCUMENT_POSITION_CONTAINS;
 }
@@ skipping 87 matching lines @@
 
 Element* TreeScope::getElementByAccessKey(const String& key) const
 {
     if (key.isEmpty())
         return 0;
     Element* result = 0;
     Node& root = rootNode();
     for (Element* element = ElementTraversal::firstWithin(root); element; element = ElementTraversal::next(*element, &root)) {
         if (equalIgnoringCase(element->getAttribute(HTMLNames::accesskeyAttr), key))
             result = element;
-        for (ShadowRoot* shadowRoot = element->youngestShadowRoot(); shadowRoot; shadowRoot = shadowRoot->olderShadowRoot()) {
+        if (ShadowRoot* shadowRoot = element->shadowRoot()) {
             if (Element* shadowResult = shadowRoot->getElementByAccessKey(key))
                 result = shadowResult;
         }
     }
     return result;
 }
 
 void TreeScope::setNeedsStyleRecalcForViewportUnits()
 {
     for (Element* element = ElementTraversal::firstWithin(rootNode()); element; element = ElementTraversal::next(*element)) {
-        for (ShadowRoot* root = element->youngestShadowRoot(); root; root = root->olderShadowRoot())
+        if (ShadowRoot* root = element->shadowRoot())
             root->setNeedsStyleRecalcForViewportUnits();
         RenderStyle* style = element->renderStyle();
         if (style && style->hasViewportUnits())
             element->setNeedsStyleRecalc(LocalStyleChange);
     }
 }
 
 } // namespace blink