Bugfixes:
- Fix benchmark parallel in node 6 #1165
- Fix memory leak with Promise.each #1057
- Fix thenable passed to .return being evaluated too early #1210
- Fix "unhandledrejection" event not having .detail field when using DOM3 event listener api #1209
- Fix Promise.join not ensuring asynchronous callback #1153
- Fix domains leaking when synchronous error is thrown while a domain is active #1125