More debugger support.

This wires up method-entry events and fixes a bug in exception events.

Change-Id: Ia7c46786a8073434fbb4546615072622f301ef84
diff --git a/src/jdwp/jdwp_handler.cc b/src/jdwp/jdwp_handler.cc
index 7914aa7..3dbf437 100644
--- a/src/jdwp/jdwp_handler.cc
+++ b/src/jdwp/jdwp_handler.cc
@@ -1482,9 +1482,7 @@
   FrameId frameId = ReadFrameId(&buf);
 
   ObjectId objectId;
-  if (!Dbg::GetThisObject(frameId, &objectId)) {
-    return ERR_INVALID_FRAMEID;
-  }
+  Dbg::GetThisObject(frameId, &objectId);
 
   uint8_t objectTag = Dbg::GetObjectTag(objectId);
   VLOG(jdwp) << StringPrintf("  Req for 'this' in frame=%llx --> %llx '%c'", frameId, objectId, (char)objectTag);