Remove unnecessary tab key press from Focus_AdvanceFocus test

The associated bug which required this extra tab is fixed.

Bug: 147644
Change-Id: Ied21533accc82613053e119aa2c5c64fc9de8343
Reviewed-on: https://chromium-review.googlesource.com/1170986
Reviewed-by: Ehsan Karamad <ekaramad@chromium.org>
Commit-Queue: Kevin McNee <mcnee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#582240}
1 file changed