[Tim Schaub (tschaub)]

This makes it possible to typecheck JSDoc types like this:

/** 
 * @typedef {function(string): boolean}
 * MyType
 */

/**
 * @param {MyType} func The function to call.
 * @param {string} arg The argument to call it with.
 * @returns {boolean} The return.
 */
function callIt(func, arg) {
  return func(arg);
}

Fixes #26774.

See also #26067.

[Tim Schaub (tschaub)]

Thanks for the quick review!