When the focus is on md-tabs, pressing shift + tab doesn't do anything

[ivan7237d]

No description provided.

[osuritz]

This can be reproduced on the demo page for tabs at https://material.angularjs.org/latest/#/demo/material.components.tabs

Steps to reproduce:

• Press [TAB] until the focus in on the md-tabs control.
• Press [TAB] and notice that the focus moves on to the next element (expected).
• Press [Shift + TAB] and notice that the focus goes back to the md-tabs control (expected)
• Press [Shift + TAB] and notice that the focus stays on md-tabs control (as opposed to focus on the previous element).

Expected behavior:

• Pressing [Shift + TAB] while the focus is on md-tabs should move the focus to the previous element

This is a pretty big accessibility issue.

[osuritz]

Anyone from the team could take a look and classify this issue?