Tree grid samples not render in IE 11.

[HristoP96]

Description

All three Tree Grid samples for do not render properly in IE 11

Steps to reproduce

Open the following link in IE 11:
https://staging.infragistics.local/products/ignite-ui-angular/angular/components/treegrid.html

Result

First sample:

Second sample:

Third sample:

Expected result

The Grids must render properly!