Switch SROA to pop Uses off the back of its visitors' queues.
Switch SROA to pop Uses off the back of its visitors' queues.

This will more closely match the behavior of the new PtrUseVisitor that
I am adding. Hopefully this will not change the actual behavior in any
way, but by making the processing order more similar help in debugging.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@169697 91177308-0d34-0410-b5e6-96231b3b80d8

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