based on the existing Number.parseInt.

Bug: v8:6791
Change-Id: I9169a4695807a3e435e343d239431ae7f6ccf2a1
Reviewed-on: https://chromium-review.googlesource.com/685990Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48241}