assert: use new language features

This adds new language features to acorn. Otherwise BigInt and other
input would not be parsed correct and would not result in nice error
messages when using simple assert.

PR-URL: https://github.com/nodejs/node/pull/27400
Refs: https://github.com/nodejs/node/issues/27391
Refs: https://github.com/nodejs/node/issues/25835


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Michaël Zasso <targos@protonmail.com>