Use isa<> instead of dyn_cast<>.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76767 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Bitcode/Writer/ValueEnumerator.cpp b/lib/Bitcode/Writer/ValueEnumerator.cpp
index aa808e2..4a6eea4 100644
--- a/lib/Bitcode/Writer/ValueEnumerator.cpp
+++ b/lib/Bitcode/Writer/ValueEnumerator.cpp
@@ -265,7 +265,7 @@
           EnumerateOperandType(Elem);
       }
     }
-  } else if (dyn_cast<MDString>(V))
+  } else if (isa<MDString>(V))
     EnumerateValue(V);
 }