fix(es/parser): Rescan << as < when parsing type args

[yannkaiser]

Description:

The related issue is a product to the fact that the lexer sees a << token in fun<<T>... and therefore parses the type args as an arrow function.

This PR adds the handling of the "split" of << when beginning to parse type args.

I am open for suggestions, I still find this a bit odd (in parse_ts_type_args()):

if is!(p, "<<") {
    p.input.cut_lshift();
} else {
    expect!(p, '<');
}

Related issue:

• Closes Parser error for type parameters containing a generic function signature #7187
• Closes Nested TypeScript generics are causing the compiler to error out #8209
• Closes An arrow function is not allowed here (related #5077) #8581

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[kdy1]

Can you add some test cases for #8209 and #7187?

[yannkaiser]

Sure, I added the test cases in the ecma_parser and swc packages, not sure if it was necessary to have in both though but i felt like it would be a good idea since the expected output is different.

[kdy1]

Thanks! It was a headache to me.

---

swc-bump:

• swc_ecma_parser