chore(dropdown): avoid IE11/Edge rendering bug
chore(dropdown): avoid IE11/Edge rendering bug

- Add `dropdown-menu` class to avoid rendering bug in IE11/Edge

Closes #5675
Fixes #5595

icfantv/bootstrap,Kpler/bootstrap,benhalverson/bootstrap,angular-ui/bootstrap,looker/bootstrap,benhalverson/bootstrap,byronigoe/bootstrap,shootermv/bootstrap,Foxandxss/bootstrap,caoruiy/bootstrap,looker/bootstrap,christor/bootstrap,benhalverson/bootstrap,wesleycho/bootstrap,vfiles/bootstrap,Servoy/bootstrap,angular-ui/bootstrap,Foxandxss/bootstrap,BookingBug/bootstrap,christor/bootstrap,fpipita/bootstrap,shootermv/bootstrap,byronigoe/bootstrap,RobJacobs/bootstrap,fpipita/bootstrap,BookingBug/bootstrap,vfiles/bootstrap,Kpler/bootstrap,caoruiy/bootstrap,icfantv/bootstrap,benhalverson/bootstrap,RobJacobs/bootstrap,wesleycho/bootstrap,Servoy/bootstrap