Throw errors in Function functions

Closes https://github.com/jashkenas/underscore/issues/1576.
Nope. Thinking of `_.bind(console.log, console)`. Currently in IE8 it will throw an error. With this patch it'll execute the `log()` logging `undefined` then return the bound function. Once the bound function is executed it will attempt `log.apply` and error out because it doesn't exist.