The DoMouseClick helper is also removed because no other caller can now pass a null aEvent. Other MouseClicked implementations are also updated since aEvent cannot be null, which was already the case.
MozReview-Commit-ID: 3bTJ6cZW9ZA
--HG--
extra : rebase_source : ae1bafe7144f6f428e2ef4e7047d5c64e0a19e8c