Just call it JS already. Forget about the "Java" bit, as JS really doesn't have much to do with Java anymore. Forget about ECMA as well -- that's a mouthful -- though I strongly suspect that the people who design JS believe verbosity is a virtue in all of their naming schemes.

Just call it JS and invite the community to come up with whatever silly backronym they see fit. Just super? Jihad script? Jelly sandwich? Juniper spirit? Other languages have been doing it for decades, so why not?