[parser] Disallow numeric separators in legacy octal like integers

[zant]

Q	A
Patch: Bug Fix?	Yes, Spec compliance 👓
Major: Breaking Change?	No
Tests Added + Pass?	Yes
Any Dependency Changes?	No
License	MIT

The follow code should throw an error if the numeric separator plugin is enabled:

Input Code

• REPL: https://babeljs.io/repl#?babili=false&browsers=&build=&builtIns=false&spec=false&loose=false&code_lz=AzD6yA&debug=false&forceAllTransforms=false&shippedProposals=false&circleciRepo=&evaluate=false&fileSize=false&timeTravel=false&sourceType=script&lineWrap=true&presets=env&prettier=false&targets=&version=7.6.2&externalPlugins=%40babel%2Fplugin-syntax-numeric-separator%407.2.0%2C%40babel%2Fplugin-syntax-bigint%407.4.4

00_0

Expected behavior/code
It should throw Invalid Invalid numeric separator after leading 0 error.

The Legacy Octal Like Decimal is defined as:

LegacyOctalLikeDecimalIntegerLiteral
0 OctalDigit
LegacyOctalLikeDecimalIntegerLiteral OctalDigit

OctalDigit
0 1 2 3 4 5 6 7

Reference

[babel-bot]

Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/11702/

[nicolo-ribaudo]

Thanks!

[zant]

Thanks to you! Super glad to contribute :)