Adds the remaining saturating float to int conversion opcodes.

Bug: v8:7226
Change-Id: If84e564a7816eb4aedbc336f5c2e614da22bb10a
Reviewed-on: https://chromium-review.googlesource.com/905472
Commit-Queue: Karl Schimpf <kschimpf@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51157}