This fixes the signature of "Math.min" and "Math.max" for integer values
from "(int, int...) -> signed" to "(signed, signed..) -> signed" which
properly distinguishes signed from unsigned values now. This is in sync
with the spec errata (and ECMAScript semantics).

R=clemensh@chromium.org
TEST=mjsunit/regress/regress-6838-1
BUG=v8:6838

Change-Id: Id72836513dd86e93472a22cf1ac2e2d382ed4f23
Reviewed-on: https://chromium-review.googlesource.com/681357
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48139}