Port d7ece57e

Original Commit Message:

    Optimization marker and the optimized code used to share the same slot
    in the feedback vector as they were mutually exclusive. With turboprop
    we would want to mark the function for tier up to Turbofan while holding
    the optimized code for Turboprop. So this cl uses the existing padding
    field to hold the optimization marker instead.

    As a driveby, removes unused JSFunction::ClearOptimizedCodeSlot function
    and fixes a minor bug in Runtime_GetOptimizationStatus.

R=mythria@chromium.org, joransiu@ca.ibm.com, junyan@redhat.com, midawson@redhat.com
BUG=
LOG=N

Change-Id: Ie635fd05c26f70124076b9c51c0c70a2b948af69
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2505621Reviewed-by: Junliang Yan <junyan@redhat.com>
Commit-Queue: Milad Fa <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/master@{#70854}