Revert "[analyzer] Remove an unused variable"

This reverts commit 2fa3e3edc4ed6547cc4ce46a8c79d1891a5b3b36.

Removed the wrong variable.

llvm-svn: 329445
diff --git a/clang/lib/Analysis/LiveVariables.cpp b/clang/lib/Analysis/LiveVariables.cpp
index de2836d..b8ea1e9 100644
--- a/clang/lib/Analysis/LiveVariables.cpp
+++ b/clang/lib/Analysis/LiveVariables.cpp
@@ -381,7 +381,7 @@
 void TransferFunctions::VisitDeclRefExpr(DeclRefExpr *DR) {
   const Decl* D = DR->getDecl();
   bool InAssignment = LV.inAssignment[DR];
-  if (isa<BindingDecl>(D)) {
+  if (const auto *BD = dyn_cast<BindingDecl>(D)) {
     if (!InAssignment)
       val.liveBindings = LV.BSetFact.add(val.liveBindings, BD);
   } else if (const auto *VD = dyn_cast<VarDecl>(D)) {