Add the JSSegmenter and hook up constructor,
supportedLocales and resolvedOptions only
Desgin Doc- https://goo.gl/fgc2Cp

TBR: bmeurer@chromium.org
Bug: v8:6891
Cq-Include-Trybots: luci.v8.try:v8_linux_noi18n_rel_ng
Change-Id: Ief25fb31d724c55c43c0fdf3080294fa83486e4f
Reviewed-on: https://chromium-review.googlesource.com/c/1247362
Commit-Queue: Frank Tang <ftang@chromium.org>
Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56393}