Add validate object, clean up stack indirect reference table.

Change-Id: Ifb329ae7d3bede3e95d48e6761cee1412a33d867
diff --git a/src/heap.h b/src/heap.h
index 4d45366..1e56778 100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -33,6 +33,9 @@
   // Allocates and initializes storage for an object instance.
   static Object* AllocObject(Class* klass, size_t num_bytes);
 
+  // Check sanity of given reference
+  static void VerifyObject(Object *obj);
+
   // Initiates an explicit garbage collection.
   static void CollectGarbage();