Bug: super method call within async arrow within class method fails

[developit]

The async-arrows-in-class transform uses Babel's arrowFunctionToExpression() helper, which doesn't patch calls to super methods:

Input:	Output:
class A extends B { a() { (async () => { super.b(); })(); } }	class A extends B { a() { (async function () { super.b(); // this is invalid })(); } }

Here's the bug reproduced in the Babel repl.

[nicolo-ribaudo]

I'd consider this a bug in arrowFunctionToExpression itself rather than in this plugin.

EDIT: Ok no, the fix relies on injecting new sync arrow functions so if cannot be done in arrowFunctionToExpression. I think we have something like hoistFunctionEnvironment somewhere that will help.