Off-thread compilation currently doesn't support adding DebugInfo to a
SharedFunctionInfo, so it also doesn't support adding coverage info.

For now, disable off-thread finalization entirely when block coverage
is enabled. In the future we most likely want to add support for this.

Bug: chromium:1011762
Change-Id: I7fdcee48f427d0f7061e90602d9d7557a98e54bb
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2126911
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67354}