Don't trigger namespaced events, it breaks VisualEditor

Code like $input.trigger( 'focus.ime' ); doesn't make any sense. Event
namespaces exist for binding and unbinding and are irrelevant when
triggering. However, there's a bug in the version of jQuery that we
use (1.8.3) that causes .trigger( 'focus.ime' ) to perform a native
focus and call natively bound focus handlers, but only call jQuery
event handlers bound to 'focus.ime', not handlers bound to 'focus'.
This bug is fixed in jQuery 1.9+. http://jsfiddle.net/WGy9h/3/
demonstrates this bug.

The way ULS broke VE with this went like this:
* VE initializes and creates two contentEditable divs, the
  pasteTarget and the documentNode. It then focuses the documentNode.
* ULS loads jQuery.ime
* Once jQuery.ime loads, it first calls .trigger( 'focus.ime' ) on
  the pasteTarget
* jQuery focuses the pasteTarget, which means a blur is emitted on the
  documentNode
* In response to this blur event, VE disables the SurfaceObserver
* jQuery.ime then calls .trigger( 'focus.ime' ) on the documentNode
* jQuery focuses the documentNode, but does not call VE's focus handler
  because it's bound to 'focus' rather than 'focus.ime'
* This means VE's SurfaceObserver is not reenabled
* If the user then focuses something else then focuses VE again, a
  native focus event fires and the SurfaceObserver does get reenabled

Change-Id: I7c590599df4cf62418403bc1d1dccfc3c6db5fd3