Remove backface-visibility from progress bars.
Remove backface-visibility from progress bars.

BS3 commit cc5e661

ztx1491/todc-bootstrap,todc/todc-bootstrap,2947721120/googlebt4,up2vs/todc-bootstrap,todc/todc-bootstrap,mozillo/todc-bootstrap,aaroncnhk/todc-bootstrap,todc/todc-bootstrap,2947721120/todc-bootstrap