sync RSVP 3.0.7

The test failure on 371 of defered_test.js:

RSVP’s latest performance tuning reduced many unneeded nextTick’s. In this specific scenario, with no subscribers the promise did not need to publish its state change and now it correctly does not.
Merge pull request #4972 from stefanpenner/rsvp

sync RSVP 3.0.7