* Use core-js promise polyfill for nomodule browsers
Also updated to the core-js@3 features modules instead of importing the exact modules directly.
Fixes#10966
* Simplify reflect and regexp
* Add ie11 test for bad Promise
* Add test script for regexp and ie11
Co-authored-by: JJ Kasper <jj@jjsweb.site>
Co-authored-by: Joe Haddad <joe.haddad@zeit.co>