The instruction is the same as the existing {select} instruction with
type. Both inputs must be in a sub-type relationship with the type
specified in the type instruction.

R=clemensh@chromium.org

Bug: v8:7581
Change-Id: Ibead6cd0253210828c8114336ea0942e6cbd6126
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1631413
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61886}