Introduce analysis pass to compute PostDominators in the new pass manager. NFC

Differential Revision: http://reviews.llvm.org/D17537

llvm-svn: 261882
diff --git a/llvm/lib/CodeGen/MachineRegionInfo.cpp b/llvm/lib/CodeGen/MachineRegionInfo.cpp
index 7d61792..0f7ebb3 100644
--- a/llvm/lib/CodeGen/MachineRegionInfo.cpp
+++ b/llvm/lib/CodeGen/MachineRegionInfo.cpp
@@ -104,7 +104,7 @@
 void MachineRegionInfoPass::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.setPreservesAll();
   AU.addRequiredTransitive<DominatorTreeWrapperPass>();
-  AU.addRequired<PostDominatorTree>();
+  AU.addRequired<PostDominatorTreeWrapperPass>();
   AU.addRequired<DominanceFrontier>();
 }