[3841442] Groups containing child shape layers with duplicate names apply the same fill class to those layers.

https://git.corp.adobe.com/edgecclayout/crema/issues/602

Test file: http://adobe.ly/1rqwAtE

Steps:
1. Open the groups in Crema
2. Note the svg preview, or generate svg and examine

Result: Groups with child layers with duplicate layer names assign them the same class for fill (cls-3). Expected: Each child layer would have its own fill class as defined in the svg file.
