The comma was removed as part of this CL: https://crrev.com/c/1355144
But layout tests rely on this: https://crrev.com/c/1372232
Thus add it back.

R=mslekova@chromium.org
CC=ahaas@chromium.org, ssauleau@igalia.com

Change-Id: I522cc9b448e5cf046074bf635bd9fc60ccf64795
Reviewed-on: https://chromium-review.googlesource.com/c/1373549Reviewed-by: Maya Lekova <mslekova@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58178}