Hi rob, unfortunately i trashed gc on my pc long time ago so i can't investigate properly your issue.
However i see those "" charachters that make me think that you're having an issue with BOM UTF-8 encoding.
I really don't know how c2runtime.js file is encoded during an export since i never had an issue with it, my empirical suggestion is to open your c2runtime.js file with an advanced text editor (ex. Notepad++) and save it with the �Encode as UTF-8 without BOM� option.
Here's an explanation of what seems to be your problem.