Fix case where we should use dyn_cast instead of cast.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@65956 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/SVals.cpp b/lib/Analysis/SVals.cpp
index 824d722..2017c4b 100644
--- a/lib/Analysis/SVals.cpp
+++ b/lib/Analysis/SVals.cpp
@@ -288,7 +288,7 @@
 SVal SVal::GetRValueSymbolVal(SymbolManager& SymMgr, const MemRegion* R) {
   SymbolRef sym = SymMgr.getRegionRValueSymbol(R);
                                 
-  if (const TypedRegion* TR = cast<TypedRegion>(R))
+  if (const TypedRegion* TR = dyn_cast<TypedRegion>(R))
     if (Loc::IsLocType(TR->getRValueType(SymMgr.getContext())))
       return Loc::MakeVal(sym);