[touch-events] standardize initTouchEvent (#29)

The WebEvents working group previously decided not to normatively specify `initTouchEvent` because there were differences in implementation and weird extra co-ordinate parameters that made no sense.

However, according to an [httparchive search](http://bigqueri.es/t/analyzing-html-css-and-javascript-response-bodies/442) there is a non-trivial amount of usage of this API (1236 of the top 300k websites as of Aug 2014).  For example: [https://www.fieldandrurallife.com/](https://www.fieldandrurallife.com/) and [http://www.arccjournals.com/](http://www.arccjournals.com/).  In both cases it looks like it's just being used as a form of touch feature detection.

However, Chrome UMA data [indicates](https://www.chromestatus.com/metrics/feature/popularity#V8TouchEvent_InitTouchEvent_Method) that `initTouchEvent` is virtually never called in practice on Chrome.  I wonder why?

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Reply to this email directly or view it on GitHub:
https://github.com/w3c/touch-events/issues/29