webadmin: The scroll bar is not aligned with the Edit Role menu box

In edit role dialog the permissions tree
scroll bar is not aligned with edit role
menu box

Change-Id: I03e80765cffddd77c95d80ee386bbea4fd16d620
Bug-Url: https://bugzilla.redhat.com/1128449
Signed-off-by: Ravi Nori <rnori@redhat.com>