Mark fast/js/const.html for auto rebaseline

It was temporarily skipped to allow for a v8 roll that changed the exact
wording of the type error thrown by this test

BUG=none
TBR=yurys@chromium.org

Review URL: https://codereview.chromium.org/231973005

git-svn-id: svn://svn.chromium.org/blink/trunk@171278 bbb929c8-8fbe-4397-9dbb-9b2b20218538