[DataFormatter] Remove dead code for the NSDictionary formatter.
[DataFormatter] Remove dead code for the NSDictionary formatter.

I'm going to make changes in this area soon, so I figured I
could clean things a bit while I was around.

git-svn-id: 4c4cc70b1ef44ba2b7963015e681894188cea27e@327445 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/lldb,apple/swift-lldb,llvm-mirror/lldb,llvm-mirror/lldb,apple/swift-lldb,apple/swift-lldb,llvm-mirror/lldb,apple/swift-lldb,llvm-mirror/lldb,apple/swift-lldb,apple/swift-lldb