They weren't initializing the VM at the start of the test. Also updated
the test description.

Bug: v8:7790
Change-Id: I7b9df9e3aebb43fc526e16ec260aa071c0fdeb92
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2615019
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71978}