This adds support for f32.min and f32.max, implemented on ia32, x64,
mips and mips64.

R=ahaas@chromium.org

Bug: v8:6600
Change-Id: If73abf3cf46011ba84158ed2ec02d074adcf4ba2
Reviewed-on: https://chromium-review.googlesource.com/1027841
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52803}