Add JDWP ReferenceType.ClassObject handler.

For bug 2157236.
diff --git a/vm/Debugger.c b/vm/Debugger.c
index 3119350..86adbb6 100644
--- a/vm/Debugger.c
+++ b/vm/Debugger.c
@@ -512,6 +512,15 @@
 }
 
 /*
+ * Convert a RefTypeId to an ObjectId.
+ */
+ObjectId dvmDbgGetClassObject(RefTypeId id)
+{
+    ClassObject* clazz = refTypeIdToClassObject(id);
+    return objectToObjectId((Object*) clazz);
+}
+
+/*
  * Return the superclass of a class (will be NULL for java/lang/Object).
  */
 RefTypeId dvmDbgGetSuperclass(RefTypeId id)