Reenable browser test for Infobars on Windows

The test was disabled waiting for https://crrev.com/c/1617498
to land.

Bug: 927949
Change-Id: Ie1d555d21eb21d04b4b859ff007767d8bb77847b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1643529
Auto-Submit: Guido Urdaneta <guidou@chromium.org>
Commit-Queue: Peter Kasting <pkasting@chromium.org>
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/master@{#666006}