When we make

@Js 
mixin DynamicBugMixin
{
  Int size() { 0 }
}

@Js 
class DynamicBug : DynamicBugMixin
{
}

And then try to

d := DynamicBug()
if (d->size != 0) throw Err.make("size != 0")

we are getting sys::UnknownSlotErr: Main::DynamicBug.size

But if we do override of the slot

@Js 
class DynamicBug : DynamicBugMixin
{
  override Int size() { DynamicBugMixin.super.size }
}

Everything will be fine.

If a slot is inherited from a class, its dynamic invocation works too.

Promoted to ticket #1386 and assigned to andy

Ticket resolved in 1.0.70

Fixed - changeset