This will be used to enforce a consistent ordering on MutationRecord delivery (oldest-to-newest).
(In reply to comment #1)
Thanks! The one thing missing is that the intent (and the WebKit impl, at least) is to keep looping over the observers until all the queues are empty. This ensures that multiple observers can interact with each other while still preserving the feature that observers hear about dom changes before a paint.
Ok, I think I got that covered now (as well as removal of transient observers): https://bitbucket.org/ms2ger/dom-core/changeset/c6ad9b7a9dff