Update bob_test.spec.js

I had a problem with this that cost me several hours of head-scratching until I figured out that the original version (on OS X 10.9.5) of the test spec required that I call my Javascript file "bob" rather than "bob.js". Am I doing something wrong here? Anyway, "fixing" this to conform to my other submission so it will run (and fail) "out of the box".