Summary:
Changelog: [Internal]
If generators are provided natively, that should suggest that the JS source
code did not go through the regenerator-transform (e.g. in Metro Hermes profile),
then there is no need to set up the regenerator runtime.
This should save some work during the Core initialization.
Reviewed By: motiz88
Differential Revision: D29986751
fbshipit-source-id: 129f5122e8e4c05535ee2aa5da6970a66843e8cd