Replace many [TreatReturnedNullStringAs=Null] with nullable DOMString

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 33 matching lines @@
 
     [CustomElementCallbacks, RaisesException, TypeChecking=Interface] Node importNode(Node node, optional boolean deep);
     [CustomElementCallbacks, RaisesException] Element createElementNS([TreatNullAs=NullString] DOMString namespaceURI, DOMString qualifiedName);
     [RaisesException, DeprecateAs=DocumentCreateAttributeNS] Attr createAttributeNS([TreatNullAs=NullString,Default=Undefined] optional DOMString namespaceURI,
                                                                                   [TreatNullAs=NullString,Default=Undefined] optional DOMString qualifiedName); // Removed from DOM4.
     HTMLCollection getElementsByTagNameNS([TreatNullAs=NullString] DOMString namespaceURI, DOMString localName);
     [PerWorldBindings] Element getElementById(DOMString elementId);
 
     // DOM Level 3 Core
 
-    [TreatReturnedNullStringAs=Null, MeasureAs=DocumentInputEncoding] readonly attribute DOMString inputEncoding; // Removed from DOM4.
+    [MeasureAs=DocumentInputEncoding] readonly attribute DOMString? inputEncoding; // Removed from DOM4.
 
-    [TreatReturnedNullStringAs=Null, MeasureAs=DocumentXMLEncoding] readonly attribute DOMString xmlEncoding; // Removed from DOM4.
-    [TreatReturnedNullStringAs=Null, TreatNullAs=NullString, RaisesException=Setter, MeasureAs=DocumentXMLVersion] attribute DOMString xmlVersion; // Removed from DOM4.
+    [MeasureAs=DocumentXMLEncoding] readonly attribute DOMString? xmlEncoding; // Removed from DOM4.
+    [RaisesException=Setter, MeasureAs=DocumentXMLVersion] attribute DOMString? xmlVersion; // Removed from DOM4.
     [RaisesException=Setter, MeasureAs=DocumentXMLStandalone] attribute boolean xmlStandalone; // Removed from DOM4.
 
     [RaisesException, CustomElementCallbacks, TypeChecking=Interface] Node adoptNode(Node node);
 
-    [TreatReturnedNullStringAs=Null, ImplementedAs=url] readonly attribute DOMString documentURI;
+    [ImplementedAs=url] readonly attribute DOMString? documentURI;
 
     // DOM Level 2 Events (DocumentEvents interface)
 
     [RaisesException] Event createEvent(DOMString eventType);
 
     // DOM Level 2 Traversal and Range (DocumentRange interface)
 
     Range createRange();
 
     // DOM Level 2 Traversal and Range (DocumentTraversal interface)
@@ skipping 66 matching lines @@
     [TreatReturnedNullStringAs=Undefined] readonly attribute DOMString readyState;
 
     Element            elementFromPoint([Default=Undefined] optional long x,
                                         [Default=Undefined] optional long y);
     [MeasureAs=DocumentCaretRangeFromPoint]
     Range              caretRangeFromPoint([Default=Undefined] optional long x,
                                            [Default=Undefined] optional long y);
 
     // Mozilla extensions
     Selection          getSelection();
-    [TreatReturnedNullStringAs=Null] readonly attribute DOMString characterSet;
+    readonly attribute DOMString? characterSet;
 
     // WebKit extensions
 
-    [TreatReturnedNullStringAs=Null] readonly attribute DOMString preferredStylesheetSet;
-    [TreatReturnedNullStringAs=Null, TreatNullAs=NullString] attribute DOMString selectedStylesheetSet;
+    readonly attribute DOMString? preferredStylesheetSet;
+             attribute DOMString? selectedStylesheetSet;
 
     [MeasureAs=DocumentGetCSSCanvasContext] RenderingContext getCSSCanvasContext(DOMString contextId, DOMString name, long width, long height);
 
     // HTML 5
     HTMLCollection getElementsByClassName(DOMString classNames);
     readonly attribute Element activeElement;
     boolean hasFocus();
 
     readonly attribute DOMString compatMode;
 
@@ skipping 52 matching lines @@
     // TODO(davidben): This is a property so attaching a deprecation warning results in false positives when outputting
     // document in the console. It's possible http://crbug.com/43394 will resolve this.
     [MeasureAs=PrefixedPageVisibility, ImplementedAs=visibilityState] readonly attribute DOMString webkitVisibilityState;
     [MeasureAs=PrefixedPageVisibility, ImplementedAs=hidden] readonly attribute boolean webkitHidden;
 
     readonly attribute HTMLScriptElement currentScript;
 };
 
 Document implements GlobalEventHandlers;
 Document implements ParentNode;