Unibrow is currently at Unicode version 7.0.0, which does not
include mongolian vowel separator (\u180E) as white space. In
order to appease test262 at the time however we kept it as a
whitespace.

Test262 has since then been updated. And while this is not an
update of unibrow, we are removing \u180E as white space here.

R=jshin@chromium.org, littledan@chromium.org
BUG=v8:5155

Review-Url: https://codereview.chromium.org/2720953003
Cr-Commit-Position: refs/heads/master@{#43485}