Bug 50680: Use mouseup rather than keyup to open search overlay

Keyup seems to work on both Windows Phone 7 and 8
If statement and waiting for keydown seems unncessary. the focus
via a mouseup or touchend is enough

Bug: 50680
Change-Id: Iab1de24c21d1f937a793830ec23d90ab5c30f9a2
Merge "Bug 50680: Use mouseup rather than keyup to open search overlay"