File manager CSS: restore files-ng .file-row transparent border

CL:1943774 removed the transparent border from .file-row, however that
causes the .eject-icon to shift 1px when it is pressed.

Restore the 1px border, so the .eject-icon is always drawn in the same
place when pressed or not.

Tbr: adanilo
Bug: 992819
Change-Id: I1d105be48798f5c5c0c93f6f85f7302135459235
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1954797
Reviewed-by: Noel Gordon <noel@chromium.org>
Commit-Queue: Noel Gordon <noel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#723147}
1 file changed