The ScheduleEarly phase of the scheduler initializes the minimum_block
values which are only required for loop hoisting. If there are no loops,
running this step is unecessary overhead.

BUG=v8:9684

Change-Id: Iba181fd55ecd634c05d3f8eb4282bd0be3141c21
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2880538Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74445}