Highlight error in <…> regrex

[hsmyers]

Highlighting iis wrong until restored by bogus match.

Example Code

token annotation-text {
    <[^_<>]>
    <-["]>+
}
# " # vscode highlight bug in Perl 6 Atom Grammar

### Picture [optional]
> Providing a picture means that if the issue is fixed and linguist updates to include the fix (linguist uses this package to highlight Perl 6 on GitHub), your issue will remain historically viewable.

### Leave this in. For internal use.
- [ ] Fixed in Master
- [ ] Fixed in Release
- [ ] Has Tests
- [ ] Passes Tests