Igniteui-angular: igxDialog is not positioned correctly under IE11

[kacheshmarova]

Description

igxDialog is not positioned in the middle of the container under IE11

• igniteui-angular version: 7.2
• browser: Internet Explorer 11

Steps to reproduce

1. Open this sample
2. Click any of the "Show Dialog" buttons. For example, the one for "Standard Dialog"
3. Observe dialog`s position

Result

Dialog is positioned in the bottom right corner.

Expected result

Dialog window to be positioned in the middle (as it is in Chrome)

[damyanpetev]

@Aleksandyr @wnvko This is totally the position: absolute + flex in IE11 messing up.
Did we not make it relative just for that reason when using flex(Global) positioning?

[wnvko]

No we did not, but we had to.