Update LoopSimplify to require and preserve DominatorTree only.

Now LoopSimplify does not require nor preserve ETForest.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37512 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Analysis/Dominators.h

@@ -195,6 +195,10 @@ protected:
       return NULL;
     return Common->getData<BasicBlock>();
   }
+
+  /// isReachableFromEntry - Return true if A is dominated by the entry
+  /// block of the function containing it.
+  const bool isReachableFromEntry(BasicBlock* A);
   
   /// dominates - Returns true iff this dominates N.  Note that this is not a
   /// constant time operation!