(spatnav) Space&enter should be entered to box instead of simulating click on it.

This fixes the regression after https://codereview.chromium.org/16959002/
which makes it impossible to enter spaces into edit boxes
in spatial navigation mode.

Bug is reproducible only with spatial navigation enabled.
So is this fix.

BUG=

Review URL: https://chromiumcodereview.appspot.com/20560005

git-svn-id: svn://svn.chromium.org/blink/trunk@155993 bbb929c8-8fbe-4397-9dbb-9b2b20218538