Added an internal function to handle `debounce` in demo.
Added an internal function to handle `debounce` in demo.

Please see this [Google Closure compiler PR](https://github.com/google/closure-compiler/pull/1170) for more information/reference.

Basically, the demo code is using `$mdUtil`, which is not part of the public API, and therefore not suitable for the public (docs) reference.
dlochrie/material,dlochrie/material,dlochrie/material,dlochrie/material