Polymer/core-overlay — pull request #32 by jeffposnick (2014-10-27 20:35:12+00:00)
Title: Check getTransition(old) return value

This works around

TypeError: Cannot read property 'teardown' of undefined
at core-overlay.Polymer.transitionChanged (http://jeffposnick.github.io/pageable-text/components/core-overlay/core-overlay.html:312:32)

runtime exceptions that I see in [this demo](http://jeffposnick.github.io/pageable-text/components/pageable-text/demo.html).

I'm not using `` directly, and I assume the errors come from using ``. The value of `old` is `"core-transition-fade"` when this exception is thrown.