We divide character ranges into
- BMP, matched normally.
- non-BMP, matched as alternatives of surrogate pair ranges.
- lone surrogates, matched with lookaround assertion that its indeed lone.

R=erik.corry@gmail.com
BUG=v8:2952
LOG=N

Review URL: https://codereview.chromium.org/1578253005

Cr-Commit-Position: refs/heads/master@{#33432}