Node.prototype.baseURI should not be nullable

third_party/WebKit/Source/core/dom/Node.idl

 /*
  * Copyright (C) 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Samuel Weinig <sam.weinig@gmail.com>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 20 matching lines @@
     const unsigned short ENTITY_NODE = 6; // historical
     const unsigned short PROCESSING_INSTRUCTION_NODE = 7;
     const unsigned short COMMENT_NODE = 8;
     const unsigned short DOCUMENT_NODE = 9;
     const unsigned short DOCUMENT_TYPE_NODE = 10;
     const unsigned short DOCUMENT_FRAGMENT_NODE = 11;
     const unsigned short NOTATION_NODE = 12; // historical
     [ImplementedAs=getNodeType] readonly attribute unsigned short nodeType;
     readonly attribute DOMString nodeName;
 
-    readonly attribute DOMString? baseURI;
+    readonly attribute USVString baseURI;
 
     [Measure] readonly attribute boolean isConnected;
     [PerWorldBindings] readonly attribute Document? ownerDocument;
     [PerWorldBindings] readonly attribute Node? parentNode;
     [PerWorldBindings] readonly attribute Element? parentElement;
     [ImplementedAs=hasChildren] boolean hasChildNodes();
     [SameObject, PerWorldBindings] readonly attribute NodeList childNodes;
     [PerWorldBindings] readonly attribute Node? firstChild;
     [PerWorldBindings] readonly attribute Node? lastChild;
     [PerWorldBindings] readonly attribute Node? previousSibling;
@@ skipping 20 matching lines @@
 
     DOMString? lookupPrefix(DOMString? namespaceURI);
     DOMString? lookupNamespaceURI(DOMString? prefix);
     boolean isDefaultNamespace(DOMString? namespaceURI);
 
     [CEReactions, CustomElementCallbacks, PerWorldBindings, RaisesException] Node insertBefore(Node node, Node? child);
     [CEReactions, CustomElementCallbacks, PerWorldBindings, RaisesException] Node appendChild(Node node);
     [CEReactions, CustomElementCallbacks, PerWorldBindings, RaisesException] Node replaceChild(Node node, Node child);
     [CEReactions, CustomElementCallbacks, RaisesException] Node removeChild(Node child);
 };