See https://github.com/mathiasbynens/es-regexp-unicode-property-escapes

Changes:
- only allow General Category, binary properties, Script, and Script_Extensions.
- implement Script_Extensions.

R=littledan@chromium.org
BUG=v8:4743

Review-Url: https://codereview.chromium.org/2502933002
Cr-Commit-Position: refs/heads/master@{#41091}

Flags removed (all begin with "harmony-"):
  function-name
  instanceof
  iterator-close
  unicode-regexps
  regexp-exec
  regexp-subclass
  species

BUG=v8:3566, v8:3648, v8:3699, v8:4093, v8:4447, v8:4602

Review-Url: https://codereview.chromium.org/2096933002
Cr-Commit-Position: refs/heads/master@{#37235}

Also make the syntax a bit less complicated and speculative.

R=littledan@chromium.org
BUG=v8:4743
LOG=N

Review URL: https://codereview.chromium.org/1845243002

Cr-Commit-Position: refs/heads/master@{#35344}