Set default document urls to 'about:blank'.

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

 /*
  * Copyright (C) 2006, 2007, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2006, 2007 Samuel Weinig <sam@webkit.org>
  *
  * 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 19 matching lines @@
 // https://wicg.github.io/cors-rfc1918/#feature-detect
 enum AddressSpace { "local", "private", "public" };
 
 typedef (HTMLScriptElement or SVGScriptElement) HTMLOrSVGScriptElement;
 
 // https://dom.spec.whatwg.org/#interface-document
 
 // FIXME: Document should have a constructor. crbug.com/238234
 interface Document : Node {
     [SameObject] readonly attribute DOMImplementation implementation;
-    readonly attribute DOMString URL;
+    [ImplementedAs=urlForBinding] readonly attribute DOMString URL;
     // FIXME: documentURI should not be nullable.
-    [ImplementedAs=url] readonly attribute DOMString? documentURI;
+    [ImplementedAs=urlForBinding] readonly attribute DOMString? documentURI;
     [MeasureAs=DocumentOrigin] readonly attribute DOMString origin;
     [RuntimeEnabled=suborigins] readonly attribute DOMString suborigin;
     readonly attribute DOMString compatMode;
 
     readonly attribute DOMString characterSet;
     [ImplementedAs=characterSet] readonly attribute DOMString charset; // legacy alias of .characterSet
     [ImplementedAs=characterSet] readonly attribute DOMString inputEncoding; // legacy alias of .characterSet
     readonly attribute DOMString contentType;
 
     readonly attribute DocumentType? doctype;
@@ skipping 155 matching lines @@
     [RuntimeEnabled=ExperimentalContentSecurityPolicyFeatures] attribute EventHandler onsecuritypolicyviolation;
     attribute EventHandler onselectionchange;
     attribute EventHandler onselectstart;
     attribute EventHandler onwheel;
 };
 
 Document implements GlobalEventHandlers;
 Document implements ParentNode;
 Document implements NonElementParentNode;
 Document implements DocumentOrShadowRoot;