Reuse SIRT for C++ references

Change-Id: I8310e55da42f55f7ec60f6b17face436c77a979f
diff --git a/src/dex_verifier_test.cc b/src/dex_verifier_test.cc
index b72f495..0560abf 100644
--- a/src/dex_verifier_test.cc
+++ b/src/dex_verifier_test.cc
@@ -38,8 +38,8 @@
 }
 
 TEST_F(DexVerifierTest, IntMath) {
-  const ClassLoader* class_loader = LoadDex("IntMath");
-  Class* klass = class_linker_->FindClass("LIntMath;", class_loader);
+  SirtRef<ClassLoader> class_loader(LoadDex("IntMath"));
+  Class* klass = class_linker_->FindClass("LIntMath;", class_loader.get());
   ASSERT_TRUE(DexVerifier::VerifyClass(klass));
 }