Add support for Acorn ImportBatchSpecifier and ParenthesizedExpression

This adds support for Acorn's non-standard `ParenthesizedExpression` node and `ImportBatchSpecifier` node which is `ImportNamespaceSpecifier` with a `name` instead of an `id`.
using `name` instead of `id` here means tools like es6-module-transpiler will have trouble dealing with the AST. semantically, the `id` defines the identifier to be defined locally, while `name` defines the binding name from the module identifier.