Updated proposal for identifying mouse events derived from touch - 'firedFrom' method

Last week on the TECG call, we agreed
<http://www.w3.org/2015/01/06-touchevents-minutes.html#item01> to focus on
Jacob's more general API design for solving the "was this mouse event
derived from a touch event" problem
<http://lists.w3.org/Archives/Public/public-touchevents/2014Sep/0000.html>.
I've updated my document
<https://docs.google.com/document/d/1-ZUtS3knhJP4RbWC74fUZbNp6cbytG6Wen7hewdCtdo/edit?pli=1#heading=h.9e6y2wbfv394>
for this.  Feedback would be appreciated (on the list or in the document).

In particular, I'd love to collect more examples of scenarios where this
API should return true.  I also suggested behavior for non-obvious
scenarios (like MouseEvent.firedFrom*("UIEVent") and
MouseEvent.firedFrom("MouseEvent")), let me know if you think there's a
better definition.

Thanks,
   Rick