Kill MWCategoryWidget#onLookupEnter

This code was somehow broken by Ia47bc897 (wtf, how?)
Actually removing it seems to do no harm (wtf?), as far as I've been able to tell...

Bug: 72906
Change-Id: If7eb34a20cc8060b594a567278241b02a8ee327a
Merge "Kill MWCategoryWidget#onLookupEnter"