This allows liftoff compiled functions to receive f64 values as
parameters and pass f64 values as arguments to called functions.

R=titzer@chromium.org

Bug: v8:6600
Change-Id: Ie7467b424ccdf1ec8b7f7625d9439ab4ea427022
Reviewed-on: https://chromium-review.googlesource.com/926105
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51414}