Intent to ship: Event.timeStamp as DOMHighResTimeStamp

[Brian Birtles]

As of Firefox 54, I intend to turn on, by default, the code that makes
Event.timeStamp a DOMHighResTimeStamp. This makes this member a double
whose value is the number of milliseconds since the time origin.

This has been developed behind the dom.event.highrestimestamp.enabled
preference. This preference has been set to true on Windows for
Nightly/DevEdition for nearly 3 years, similarly on Linux for 1.5
years, on Mac since last December, and on Android since today. It is
disabled on beta/release for all platforms, however.

Chrome have shipped this since April last year. There were
compatibility concerns at the time but Chrome have continued shipping
this and it appears that Edge are considering making this change, and
WebKit might if either Gecko or Edge ship this[1].

(The original work on this goes back to bug 77992 which I believe
predates our "Intent to implement" practice so there is no intent to
implement mail to point to.)

Bug to turn on by default: https://bugzilla.mozilla.org/show_bug.cgi?id=1026804

Link to standard: I believe Anne is waiting on a second browser to
ship this change before updating the DOM spec: [2]

[1] https://github.com/whatwg/dom/issues/23#issuecomment-249319401
[2] https://github.com/whatwg/dom/issues/23#issuecomment-212815896

[smaug]

Especially because this should fix the old event.timeStamp handling inconsistencies, sounds really good.

-Olli