Fix Esc hotkey behavior (#7199)

This fixes following cases which causes hotkey action accidentally:

* hitting Esc key to cancel text composition (mostly in CJK)

  Although events on cancelling composition are still heavily
  browser / input method dependent, but this implementation would
  covers current UI Events spec and some exceptions.

* hitting Esc key to close autocomplete suggestions

This PR changes to use keydown event instead of keyup event as well as other hotkeys.