Only allow one shadowRoot.

sky/engine/core/dom/Element.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Peter Kelly (pmk@post.com)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012, 2013 Apple Inc. All rights reserved.
  *           (C) 2007 Eric Seidel (eric@webkit.org)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 949 matching lines @@
     return localChange;
 }
 
 void Element::recalcChildStyle(StyleRecalcChange change)
 {
     ASSERT(document().inStyleRecalc());
     ASSERT(change >= Inherit || childNeedsStyleRecalc());
     ASSERT(!needsStyleRecalc());
 
     if (change > Inherit || childNeedsStyleRecalc()) {
-        for (ShadowRoot* root = youngestShadowRoot(); root; root = root->olderShadowRoot()) {
+        if (ShadowRoot* root = shadowRoot()) {
             if (root->shouldCallRecalcStyle(change))
                 root->recalcStyle(change);
         }
 
         // This loop is deliberately backwards because we use insertBefore in the rendering tree, and want to avoid
         // a potentially n^2 loop to find the insertion point while resolving style. Having us start from the last
         // child and work our way back means in the common case, we'll find the insertion point in O(1) time.
         // See crbug.com/288225
         StyleResolver& styleResolver = document().ensureStyleResolver();
         Text* lastTextNode = 0;
@@ skipping 61 matching lines @@
     ensureElementRareData().setCustomElementDefinition(definition);
 }
 
 CustomElementDefinition* Element::customElementDefinition() const
 {
     if (hasRareData())
         return elementRareData()->customElementDefinition();
     return 0;
 }
 
-PassRefPtr<ShadowRoot> Element::createShadowRoot(ExceptionState& exceptionState)
+// TODO(esprehn): Implement the sky spec where shadow roots are a custom
+// element registration feature.
+PassRefPtr<ShadowRoot> Element::ensureShadowRoot(ExceptionState& exceptionState)
 {
+    if (ShadowRoot* root = shadowRoot())
+        return root;
     return PassRefPtr<ShadowRoot>(ensureShadow().addShadowRoot(*this));
 }
 
 ShadowRoot* Element::shadowRoot() const
 {
     ElementShadow* elementShadow = shadow();
     if (!elementShadow)
         return 0;
-    return elementShadow->youngestShadowRoot();
+    return elementShadow->shadowRoot();
 }
 
 void Element::childrenChanged(const ChildrenChange& change)
 {
     ContainerNode::childrenChanged(change);
 
     if (ElementShadow* shadow = this->shadow())
         shadow->setNeedsDistributionRecalc();
 }
 
@@ skipping 715 matching lines @@
         return false;
     // Turn off style sharing for elements that can gain layers for reasons outside of the style system.
     // See comments in RenderObject::setStyle().
     // FIXME: Why does gaining a layer from outside the style system require disabling sharing?
     if (isHTMLCanvasElement(*this))
         return false;
     return true;
 }
 
 } // namespace blink