Add .vs to .gitignore. This seems to be a new thing with VS2017. BUG=angleproject:1569 Change-Id: Ic46566b979e975e5e6eb3a1f80eac9e44b66f2d4 Reviewed-on: https://chromium-review.googlesource.com/719296 Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>