scrolling issue w/multiple long modals

[mcku]

Steps

Go to example. http://codepen.io/anon/pen/aWLdxg?editors=0011
Child modal's dimmerattribute set to true
Click the trigger button
Click the proceed button on the modal
Click on dimmer of the child modal
The child modal closes.

Expected Result

Parent modal's scrolling should work

Actual Result

It doesn't

Version

0.68.2

Testcase

http://codepen.io/anon/pen/aWLdxg?editors=0011

[marcdibold]

Duplicate #1157