Find when pressing enter. Call onClickListener in TextView.

Bug:3313519

In Find ActionMode, Enter should call find on page (rather than
advancing focus to the WebView).

In TextView, pass and Enter key down to super, so that the
pressed state can get called properly, and the
onClickListener will fire.

Change-Id: Ia875fa6b5cf02565a0d066a009e68ce97718b032