HI @garryyao

Thanks for the Pull Request! Overall, this is great, but there are a couple of things i'm a bit worried about -

1. Polymer.telemetry is going away with Polymer 2.0 - so, not something we want to rely on if we don't have to. having said that, i don't know of another way to do this, so.. we might have to live with it.
2. javascript .find doesn't work in IE at all (edge excepted), can you please re-write that so it also works in IE?

Thanks again!

Nice catches @runn-vermel.

Nice catches, as you mentioned I cannot find a better alternative to Polymer.telemetry without unexpected side-effect or potentially performance issue (e.g. the document.createElement hack) I think we can stay with this and pull-request Polymer/webcomponents.js for that.

So here is just to make the patch work on IE.

Thanks for you time on reviewing.