Set & Array extensions: Builders do not not mark threads as yielding..

[yuri-kiss]

As seen here, any function that uses a generator needs to mark this https://github.com/PenguinMod/PenguinMod-Vm/blob/develop/src/compiler/intermediate.js#L65 as true. You can get this IRScript from the script tree gen instance https://github.com/PenguinMod/PenguinMod-Vm/blob/develop/src/compiler/irgen.js#L80

[yuri-kiss]

@jwklong @DogeisCut