Use high precision timestamp for Event.timestamp

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

 /*
  * Copyright (C) 2006, 2007, 2009, 2011 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 26 matching lines @@
 
     void stopPropagation();
     void stopImmediatePropagation();
 
     readonly attribute boolean bubbles;
     readonly attribute boolean cancelable;
     void preventDefault();
     readonly attribute boolean defaultPrevented;
 
     [RuntimeEnabled=TrustedEvents, Unforgeable] readonly attribute boolean isTrusted;
-    readonly attribute DOMTimeStamp timeStamp;
+    [CallWith=ScriptState] readonly attribute DOMHighResTimeStamp timeStamp;

[Rick Byers, 2015/09/25 17:29:33]

Add a TODO here about the return type - mentioning it's sometimes actually a
DOMTimeStamp.

 
     // FIXME: initEvent()'s arguments should not be optional.
     [Measure] void initEvent([Default=Undefined] optional DOMString type,
                              [Default=Undefined] optional boolean bubbles,
                              [Default=Undefined] optional boolean cancelable);
 
     // Shadow DOM
     // https://w3c.github.io/webcomponents/spec/shadow/#extensions-to-event-interface
     [MeasureAs=EventPath, CallWith=ScriptState] readonly attribute EventTarget[] path;
 
@@ skipping 11 matching lines @@
     const unsigned short KEYPRESS  = 1024;
     const unsigned short DRAGDROP  = 2048;
     const unsigned short FOCUS     = 4096;
     const unsigned short BLUR      = 8192;
     const unsigned short SELECT    = 16384;
     const unsigned short CHANGE    = 32768;
     [MeasureAs=EventSrcElement] readonly attribute EventTarget srcElement;
     [MeasureAs=EventReturnValue, CallWith=ExecutionContext, ImplementedAs=legacyReturnValue] attribute boolean returnValue;
     [MeasureAs=EventCancelBubble] attribute boolean cancelBubble;
 };