stylelint: exit gracefully if all affected files are ignored
stylelint: exit gracefully if all affected files are ignored

Bug: chromium:1083142
Change-Id: I182e4555088b69ed15826d4d59882a09fcc3a58c
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2268387
Commit-Queue: Tim van der Lippe <dba8716ee7f8d16236046f74d2167cb94410f6ed@chromium.org>
Reviewed-by: Tim van der Lippe <dba8716ee7f8d16236046f74d2167cb94410f6ed@chromium.org>
Reviewed-by: Mathias Bynens <17a2cbc4e33156874a9862b0f530521117e66a3d@chromium.org>
Auto-Submit: Paul Irish <5f672bbedd2fccb2b3e838838e74ef989148de66@chromium.org>

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