Support slot element's fallback content feature

third_party/WebKit/Source/core/dom/shadow/ShadowRoot.h

 /*
  * Copyright (C) 2011 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.
  *     * Neither the name of Google Inc. nor the names of its
@@ skipping 60 matching lines @@
     using TreeScope::getElementById;
 
     // TODO(kochi): crbug.com/507413 In non-Oilpan, host() may return null during queued
     // event handling (e.g. during execCommand()).
     Element* host() const { return toElement(parentOrShadowHostNode()); }
     ElementShadow* owner() const { return host() ? host()->shadow() : 0; }
 
     ShadowRoot* youngerShadowRoot() const { return prev(); }
 
     ShadowRoot* olderShadowRootForBindings() const;
+    // TODO(hayato): Rename this to more less-confusing name. This is likely to be misued because isOpen() includes V0 too.
     bool isOpen() const { return type() == ShadowRootType::V0 || type() == ShadowRootType::Open; }
     bool isV1() const { return type() == ShadowRootType::Open || type() == ShadowRootType::Closed; }
 
     bool isYoungest() const { return !youngerShadowRoot(); }
     bool isOldest() const { return !olderShadowRoot(); }
 
     void attach(const AttachContext& = AttachContext()) override;
 
     InsertionNotificationRequest insertedInto(ContainerNode*) override;
     void removedFrom(ContainerNode*) override;
@@ skipping 79 matching lines @@
     return adjustedFocusedElement();
 }
 
 DEFINE_NODE_TYPE_CASTS(ShadowRoot, isShadowRoot());
 DEFINE_TYPE_CASTS(ShadowRoot, TreeScope, treeScope, treeScope->rootNode().isShadowRoot(), treeScope.rootNode().isShadowRoot());
 DEFINE_TYPE_CASTS(TreeScope, ShadowRoot, shadowRoot, true, true);
 
 } // namespace blink
 
 #endif // ShadowRoot_h