Bugfixes:
- Fix Promises/A+ compliance issue regarding circular thenables: the correct behavior is to go into an infinite loop instead of warning with an error (Fixes #682).
- Fix "(node) warning: possible EventEmitter memory leak detected" (#661).
- Fix callbacks sometimes being called with a wrong node.js domain (#664).
- Fix callbacks sometimes not being called at all in iOS 8.1 WebApp mode (#666, #687).