Parse Infinity and NaN as numbers

[guillaumebrunerie]

This change parses the tokens Infinity and NaN as numbers.
Technically, they are read-only global variables, but just like for undefined, I think it makes sense to parse and highlight Infinity and NaN as numbers instead of as identifiers.

Checklist:

• All tests pass in CI.
• The script/parse-examples passes without issues.
• There are sufficient tests for the new fix/feature.
• Grammar rules have not been renamed unless absolutely necessary.
• The conflicts section hasn't grown too much.
• The parser size hasn't grown too much (check the value of STATE_COUNT in src/parser.c).

[maxbrunsfeld]

Let's not add these to the grammar. They aren't special syntax in JavaScript; they're just built-in global variables. There is a cost to every special keyword added to the grammar. For syntax highlighting, these can be recognized via string-matching predicates.

[guillaumebrunerie]

Should the special rule for undefined be removed, then?

tree-sitter-javascript/grammar.js

Lines 1043 to 1053 in f772967

	// 'undefined' is syntactically a regular identifier in JavaScript.
	// However, its main use is as the read-only global variable whose
	// value is [undefined], for which there's no literal representation
	// unlike 'null'. We gave it its own rule so it's easy to
	// highlight in text editors and other applications.
	_identifier: $ => choice(
	$.undefined,
	$.identifier
	),

[maxbrunsfeld]

I'd be fine with that, except that a lot of existing queries may need to be updated.