This commit adds a --run-skipped flag to the test runner that will
bypass the 'SKIP' status.

Bug: v8:8485
Change-Id: Iac012bdaf2de6b0f8e44ed3a65bc9330709527bb
Reviewed-on: https://chromium-review.googlesource.com/c/1346490
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57710}