A few things:
I'm not sure everyone is aware, but ECMA formally approved the Dart language specification just a few days ago. See:
We just had the third meeting of ECMA TC52, the Dart standards committee.
We discussed enums, deferred loading, async, and minor bug fixes to the existing spec.
We decided not to vote on deferred loading, even though that is pretty much done, and rather deal with all proposed changes to the freshly minted spec later in the year. Our next meeting is in Switzerland on September 16th. The goal is to formally incorporate enums and deferred loading, and at least a subset of the async proposal, in the next rev of the spec, which we hope to get done by the end of 2014.
Bear in mind that deferred loading is shipping; the existing spec allows experimentation on that.
Wrt to enums, I will publish a revised draft proposal soon. Differences vs. the last draft are very minor.
As for async - we are working on an article to explain our plans. Since that is taking a bit longer, I want to explain where we are in a separate mail later today.