[analyzer] DynamicTypeInfo: Avoid putting null regions into dynamic typemap.

Fixes a crash.

llvm-svn: 369726
diff --git a/clang/test/Analysis/cast-value-logic.cpp b/clang/test/Analysis/cast-value-logic.cpp
index e001e4a..0d2255a 100644
--- a/clang/test/Analysis/cast-value-logic.cpp
+++ b/clang/test/Analysis/cast-value-logic.cpp
@@ -131,3 +131,8 @@
 }
 } // namespace test_get_as
 
+namespace crashes {
+void test_non_reference_null_region_crash(Shape s) {
+  cast<Circle>(s); // no-crash
+}
+} // namespace crashes