update for unicode 13.0.0 #938
Description
failing test262 tests:
- test/language/identifiers/start-unicode-13.0.0.js
- test/language/identifiers/part-unicode-13.0.0.js
- test/language/identifiers/part-unicode-13.0.0-escaped.js
- test/language/identifiers/start-unicode-13.0.0-escaped.js