Add support for lists and backward references when decoding a message to a Dart_CObject object

runtime/platform/assert.h

Index: runtime/platform/assert.h
diff --git a/runtime/platform/assert.h b/runtime/platform/assert.h
index 0bfd8eef4c2f3d935c1d9196f4c8894ab207ff33..3d39bab4eeebc59113853e24d7fe9048386ff451 100644
--- a/runtime/platform/assert.h
+++ b/runtime/platform/assert.h
@@ -62,6 +62,9 @@ class DynamicAssertionHelper {
 
   template<typename E, typename A>
   void GreaterEqual(const E& left, const A& right);
+
+  template<typename T>
+  void NotNull(const T p);
 #endif
 
  private:
@@ -196,6 +199,13 @@ void DynamicAssertionHelper::GreaterEqual(const E& left, const A& right) {
   std::string es = ess.str(), as = ass.str();
   Fail("expected: %s >= %s", es.c_str(), as.c_str());
 }
+
+
+template<typename T>
+void DynamicAssertionHelper::NotNull(const T p) {
+  if (p != NULL) return;
+  Fail("expected: not NULL, found NULL");
+}
 #endif
 
 }  // namespace dart
@@ -277,6 +287,9 @@ void DynamicAssertionHelper::GreaterEqual(const E& left, const A& right) {
 
 #define EXPECT_GE(left, right)                                                 \
   dart::Expect(__FILE__, __LINE__).GreaterEqual((left), (right))
+
+#define EXPECT_NOTNULL(ptr)                                                    \
+  dart::Expect(__FILE__, __LINE__).NotNull((ptr))
 #endif
 
 // TODO(iposva): provide a better way to get extra info on an EXPECT