As required by the spec, the second return value now returns success
also for the range between 0 and -1 where the conversion results in 0.

R=bradnelson@chromium.org, mstarzinger@chromium.org, v8-arm-ports@googlegroups.com, v8-mips-ports@googlegroups.com

Review URL: https://codereview.chromium.org/1533503002

Cr-Commit-Position: refs/heads/master@{#32936}