use Angular's zone.js for implementing zones

[jmesserly]

This gives us a way of implementing Zones that interoperates with JS, which will be helpful for Angular scenarios. It also should have less code size impact (it uses metaprogramming to hook browser callbacks, and would be opt-in).

[vsmenon]

In general, can we implement the Dart event loop on top of angular zones?

https://www.dartlang.org/articles/event-loop/

[jmesserly]

In general, can we implement the Dart event loop on top of angular zones?

yup, should be able to