Javascript/Rhino code editor is broken (blank lines)

Edit Subject

I'm trying to do the Gymnast puzzle in JavaScript (i.e. Rhino) using the in-browser code editor, and it just doesn't work--nothing shows up after the first line. The cursor moves, but I don't know if I'm writing white text on the white background or if everything is spaces or what--it's completely useless though.
If it matters, I'm running the very-common combo of IE9 on Windows 7.