IpcSender should consistently be Sync or !Sync.

[Ms2ger]

It seems like it's Sync on linux and !Sync on windows right now.

[emilio]

yeah, that's because on windows we're using mpsc, which is out of our control. Worth waiting to #108 to land?

[antrik]

@Ms2ger it should always be !Sync after #115 -- it just hasn't landed in Servo yet. (Because of unrelated regressions in other commits...)

I'm am confused though: I did believe the version currently used in Servo should actually be Sync everywhere?... Can you please elaborate why you think that's not the case?

[Ms2ger]

I didn't double-check, but I thought mpsc senders were not Sync? Anyway, we should land that.