Highlighting string interpolations in groovy throws an Error

[Peter Williams]

Trying to highlight groovy code that contains string interpolations, ex:

def sum = "The sum of 2 and 3 equals ${2 + 3}"

throws the following error:

Error: Expected `string` for `name`, got `[object Object]`

I'll link a PR to this issue that creates a failing test case and partially solves the bug. However, I think another change needs to be made to the language file in order to get the test to pass, and I'm not quite sure how to modify the babel transform you introduced in #9 in order to accomplish this.

This line would need to be changed to:

env.content = Prism.highlight(env.content.value, {