Rearrange some deckchairs. Moving the class before it's use.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173612 91177308-0d34-0410-b5e6-96231b3b80d8
Fix miscompile. Add back the use of the ArrayRef version of the ::get method.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173613 91177308-0d34-0410-b5e6-96231b3b80d8