SignatureHelper::kMarker needs an explicit instantiation after
f3b4167f.

Change-Id: Ia5a0696a576a2c59bea262359058bd63eb3c8426
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2101004
Auto-Submit: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66701}