Don't pass parseParam to wrapTracking

The `parseParam` function is just a helper that returns a boolean value, rather than a true parsing function that returns an AST node. When wrapped by `wrapTracking`, which assumes that the result of `parseFunction` is an AST node, `parseParam` becomes unusable in browsers that restrict property accesses on boolean values—for instance, in strict mode in Safari, `true.foo = value` throws "TypeError: Attempted to assign to readonly property."

cc @vjeux @jeffmo