Fix confusing Waypoint: Write Reusable JavaScript with Functions

[joel-bentley]

Fix confusing description and examples.

Remove superfluous and unneeded tests. For example,

editor.getValue().match(/return/gi).length >= 1

will always be true. The regex matches all instances of the string "return" in the code window, even the instance in the comments within the code.

closes #1936

[QuincyLarson]

Great work here, @joel-bentley! If you can spare the time to look at our other JavaScript and and OOP challenges, they could use a similar touch, too.

[joel-bentley]

Thanks @QuincyLarson !
I'll take a look and see what I can do.