Add dom info verifier.

llvm-svn: 52967
diff --git a/llvm/lib/Analysis/LoopPass.cpp b/llvm/lib/Analysis/LoopPass.cpp
index b4534cd..57e8f4d 100644
--- a/llvm/lib/Analysis/LoopPass.cpp
+++ b/llvm/lib/Analysis/LoopPass.cpp
@@ -234,6 +234,9 @@
       recordAvailableAnalysis(P);
       removeDeadPasses(P, "", ON_LOOP_MSG);
 
+      // Verify dominator information if it is available and preserved.
+      verifyDomInfo(*LP, F);
+
       if (skipThisLoop)
         // Do not run other passes on this loop.
         break;