[GraphTraits] Replace all NodeType usage with NodeRef

This should finish the GraphTraits migration.

Differential Revision: http://reviews.llvm.org/D23730


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279475 91177308-0d34-0410-b5e6-96231b3b80d8
24 files changed