Regex bug

## Bug Description
Hermes version: 0.12.0
OS version (if any): ubuntu 20.04
Hi. The code below does not have the same behavior as other engines (e.g., V8 in Google Chrome,SpiderMonkey in Firefox,chakra in Edge,quickjs,jerryscript). This test case works correctly in other js engines with returning a matched result, but in hermes return null.

## Steps To Reproduce
1.var regex=/((?:(?:|[A-Z])((?:n*.)){1}))+(?:\2\2*)/;
2.regex.exec("NnnX")


## The Expected Behavior
[ "Nnn", "n", "n" ]