Take "n" back from vim if no search result is being highlighted

Alt- doesn't work well as a modifier. Vim mode clears search
highlights if the user presses Esc on the query box, Take "n"
back in this case.

Note that vim mode behaves slightly different from the actual
vim, in which pressing Esc (twice) still keeps the results
highlighted.

Change-Id: I600b0625ecded6b1678231d4054952f532889bc5
2 files changed