In the frontend we need to know if XUL buttons in the toolbar were
triggered by a touch event, so we're passing on the inputSource
in the command event.
MozReview-Commit-ID: DMvgZULk9hT
--HG--
extra : rebase_source : c455c8ec77e439bf02c1e3e8d34a36e1fb5e3bd0