btoa was not working before it was dereferenced

In Chrome, initial setup showed an Uncaught TypeError: Illegal Invocation Error at this point.

Not sure why it wasn't working, but after dereferencing, it now encodes just fine.

Related to:
wordnik/swagger-js#63
wordnik/swagger-js#64

Tony said:
I'm not sure why this change would make any difference. It would need to go into swagger-js, though, since that is just a dependency in swagger-ui. You can send a PR there...