Recorded slots in store buffer are never in free space. Remove migration consistency check.
Recorded slots in store buffer are never in free space. Remove migration consistency check.

After establishing the invariant that the store buffer always has valid slots after marking, the store buffer integrity check is not needed anymore.

BUG=454157
LOG=n

Review URL: https://codereview.chromium.org/990173002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#27073}

UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh