Implement JDWP StackFrame.ThisObject.

I found a way to test this too.

Change-Id: Ia9451c97d5b4269f63c6b8d75f145583db7dfff5
diff --git a/src/jdwp/jdwp_handler.cc b/src/jdwp/jdwp_handler.cc
index ad02f64..9b5c080 100644
--- a/src/jdwp/jdwp_handler.cc
+++ b/src/jdwp/jdwp_handler.cc
@@ -1476,7 +1476,7 @@
   }
 
   uint8_t objectTag = Dbg::GetObjectTag(objectId);
-  LOG(VERBOSE) << StringPrintf("  Req for 'this' in thread=%llx frame=%llx --> %llx %s '%c'", threadId, frameId, objectId, Dbg::GetObjectTypeName(objectId), (char)objectTag);
+  LOG(VERBOSE) << StringPrintf("  Req for 'this' in thread=%llx frame=%llx --> %llx '%c'", threadId, frameId, objectId, (char)objectTag);
 
   expandBufAdd1(pReply, objectTag);
   expandBufAddObjectId(pReply, objectId);