Scrollbars appearing with Mat-Expansion-Panel in Mat-Tab with Edge/IE.

[flipZomb]

Bug, feature request, or proposal:

Bug, I presume

What is the expected behavior?

no "rogue" scrollbars.

What is the current behavior?

"rogue" scrollbar is appearing with Expansion Panel in Tabs. Happens with Edge and IE 11, seems ok in Chrome.

I hope the screenshots explain the issue sufficiently.

Resize the Window and this happens

But switching the tabs back and forth makes the scrollbar go away. Also minizing and then restoring ithe window makes the scrollbar go away.

What are the steps to reproduce?

https://stackblitz.com/edit/angular-r5vupv?file=app/expansion-overview-example.html

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

Material 6.3.3
Angular 6.0.9
Edge / IE11

Is there anything else we should know?

Works fine in Chrome