Mat-Select openedChange event does not work correctly in some browsers

[RandomNonameDude]

Bug, feature request, or proposal:

Mat-select's openedChange event is fired twice when the options list is closed in some browsers.

What is the expected behavior?

openedChange event should be fired only once when the options list is closed in all browsers.

What is the current behavior?

openedChange event is fired twice when the options list is closed in some browsers.

What are the steps to reproduce?

https://stackblitz.com/edit/angular-tqzukt

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

The behavior is obviously not correct.

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

Angular 6.0.2
Material 6.1.0

Edge - Win10
IE - Win7
Safari - Mac, iPhone, iPad

Is there anything else we should know?

Works ok in Chrome on Win7 and Win10.

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