Use more idiomatic assert.

llvm-svn: 151026
diff --git a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
index 5c52b88..0f2a634 100644
--- a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
+++ b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
@@ -503,8 +503,8 @@
     V = InsertNoopCastOfTo(V,
        Type::getInt8PtrTy(Ty->getContext(), PTy->getAddressSpace()));
 
-    assert(!dyn_cast<Instruction>(V) ||
-           SE.DT->properlyDominates(dyn_cast<Instruction>(V),
+    assert(!isa<Instruction>(V) ||
+           SE.DT->properlyDominates(cast<Instruction>(V),
                                     Builder.GetInsertPoint()));
 
     // Expand the operands for a plain byte offset.