The Web IDE is able to detect github-style URLs and although raw.githubusercontent.com doesn't work, it uses the GitHub API to request the file in a way which DOES work cross origin
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
Did you try it? As I said above, it works.
The Web IDE is able to detect github-style URLs and although raw.githubusercontent.com doesn't work, it uses the GitHub API to request the file in a way which DOES work cross origin