Make init*Event() arguments nullable where appropriate

third_party/WebKit/Source/core/events/TextEvent.idl

 /*
  * Copyright (C) 2007 Apple 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 19 matching lines @@
 // https://www.w3.org/Bugs/Public/show_bug.cgi?id=12958
 // https://github.com/w3c/uievents/commit/1a2aa02b474fd4feaf43fdced06e6fd7214196a4
 
 interface TextEvent : UIEvent {
 
     [Measure] readonly attribute DOMString data;
 
     [Measure, LegacyInterfaceTypeChecking] void initTextEvent([Default=Undefined] optional DOMString typeArg,
                                                               [Default=Undefined] optional boolean canBubbleArg,
                                                               [Default=Undefined] optional boolean cancelableArg,
-                                                              [Default=Undefined] optional Window viewArg,
+                                                              [Default=Undefined] optional Window? viewArg,
                                                               [Default=Undefined] optional DOMString dataArg);
 
 };