Drop support for [TreatUndefinedAs=NullString]

third_party/WebKit/Source/core/frame/Window.idl

 /*
  * Copyright (C) 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 149 matching lines @@
                                         [Default=Undefined] optional boolean wholeWord,
                                         [Default=Undefined] optional boolean searchInFrames,
                                         [Default=Undefined] optional boolean showDialog);
     [MeasureAs=WindowOffscreenBuffering, Replaceable, NotEnumerable] readonly attribute boolean offscreenBuffering;
     [MeasureAs=WindowScreenLeft, Replaceable] readonly attribute long screenLeft;
     [MeasureAs=WindowScreenTop, Replaceable] readonly attribute long screenTop;
     [MeasureAs=WindowDefaultStatus] attribute DOMString defaultStatus;
     [MeasureAs=WindowDefaultstatus, ImplementedAs=defaultStatus] attribute DOMString defaultstatus;
     [MeasureAs=StyleMedia] readonly attribute StyleMedia styleMedia;
     [DeprecateAs=GetMatchedCSSRules, LegacyInterfaceTypeChecking] CSSRuleList getMatchedCSSRules([Default=Undefined] optional Element element,
-                                                                                                 [TreatUndefinedAs=NullString, Default=Undefined] optional DOMString? pseudoElement);
+                                                                                                 [Default=Undefined] optional DOMString? pseudoElement);
     // This is the interface orientation in degrees. Some examples are:
     //  0 is straight up; -90 is when the device is rotated 90 clockwise;
     //  90 is when rotated counter clockwise.
     [MeasureAs=WindowOrientation, RuntimeEnabled=OrientationEvent] readonly attribute long orientation;
     [DeprecateAs=PrefixedRequestAnimationFrame] long webkitRequestAnimationFrame(FrameRequestCallback callback);
     [DeprecateAs=PrefixedCancelAnimationFrame, ImplementedAs=cancelAnimationFrame] void webkitCancelAnimationFrame(long id);
     [DeprecateAs=PrefixedCancelRequestAnimationFrame, ImplementedAs=cancelAnimationFrame] void webkitCancelRequestAnimationFrame(long id);
     [MeasureAs=PrefixedTransitionEventConstructor] attribute TransitionEventConstructor WebKitTransitionEvent;
     [Measure] attribute AnimationEventConstructor WebKitAnimationEvent;
     [DeprecateAs=PrefixedWindowURL] attribute URLConstructor webkitURL;
@@ skipping 28 matching lines @@
 // FIXME: make this typedef accurate once enough of http://crbug.com/240176
 // is in place.
 // FIXME: consider putting this typedef in an .idl file containing spec-wide
 // utility type definitions.
 typedef MessagePort Transferable;
 
 Window implements GlobalEventHandlers;
 Window implements WindowBase64;
 Window implements WindowEventHandlers;
 Window implements WindowTimers;