Fix inline modifiers inside lookarounds

[stulov]

Inside parseAtomAndExtendedAtom, (? used to be searched from the start of the string, rather than from the current position. So, trying to parse an expression containing nested lookarounds and inline modifiers (e.g., /(?<=(?i:un))parse(?=(?i:able))/) threw an error.

Didn't quite understand how the tests work, so didn't write one, sorry.

[JLHwung]

Didn't quite understand how the tests work, so didn't write one, sorry.

No worry. Can you add a test before

regjsparser/test/test-data-modifiers-group.json

Line 490 in c622da7

"^[a-z](?imi:[a-z])$": {

?

You can put the test regex as key and leave an empty object as value, then run node ./test/update-fixtures.js, it will update the actual AST as value and we can see if it works as expected.