@param should not error on non-functions

[sandersn]

// @noEmit: true
// @allowJs: true
// @checkJs: true
// @Filename: a.js
// from util
/** @param {function} ctor - A big long explanation follows */
exports.inherits = require('inherits') // shouldn't error -- there is no function to check here

Expected behavior:
No error -- the external documentation for util.inherits is written on the export of the internal implementation of it. This is fine. Perhaps the compiler should require the type of the initializer to have a signature with a parameter named ctor, but right now it just looks at the syntax.

Actual behavior:
An error that inherits has no parameter named ctor.