[GraphWriter] Change GraphWriter to use NodeRef in GraphTraits
[GraphWriter] Change GraphWriter to use NodeRef in GraphTraits

Summary: Corresponding LLVM patch: D23580

Reviewers: dblaikie

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D23581

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@278963 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang