js suggest: better keyup/keydown handling

js suggest: better keyup/keydown handling

some actions, like ctrl-click, trigger the keyup event even though it
has no bearing on autocomplete. This leads to extra impression-results
tracking events being fired. The existing keypress event, per spec,
handles input that normally produces a character value. The keyup /
keydown events should only be handling special non-character producing
keys that directly effect autocomplete. As such put together a list of
relevant keys and only fire on those.

Change-Id: I8d2a4fade84a5b94a81fa7ee0192912d2407ba92