Bug, feature request, or proposal:

This bug occurs intermittently. When toggling the slider quickly, the slider might not toggle however the (change) event will still fire.

https://plnkr.co/edit/zMzNTiSz6OmxbrJZSUnP?p=preview

What is the expected behavior?

The event should not fire when the value is not changed.

What is the current behavior?

The event will fire even when the value is not changed.

What are the steps to reproduce?

1. Using the Plunker provided toggle the slider quickly.
2. The last 10 event calls will be displayed
3. Occasionally, the slider will not toggle however the (change) event will still fire e.g. (true true) (false false)

What is the use-case or motivation for changing an existing behavior?

The event should not fire when the value is not changed.

Which versions of Angular, Material, OS, browsers are affected?

Tested on
Angular: 2.4.6
Material: 2.0.0-beta.2
OS: Windows
Browser: Chrome

Is there anything else we should know?

NA