Reorders the Smi check and the empty OptimizationMarker check as the
latter implies the first and means there is now just a single comparison
on the fast path.

Bug: v8:9771
Change-Id: Ibba1f322944b17186842983e227684b301ed5f31
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1833683
Commit-Queue: Dan Elphick <delphick@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64110}