AOT: Add a separate switchable call state for unlinked calls.

runtime/vm/object_service.cc

Index: runtime/vm/object_service.cc
diff --git a/runtime/vm/object_service.cc b/runtime/vm/object_service.cc
index fc956227d762b2480325f798fca5ac5bea39b734..bb0bb26d2d2c985f86528399da413ce983b6500c 100644
--- a/runtime/vm/object_service.cc
+++ b/runtime/vm/object_service.cc
@@ -754,6 +754,11 @@ void SingleTargetCache::PrintJSONImpl(JSONStream* stream, bool ref) const {
 }
 
 
+void UnlinkedCall::PrintJSONImpl(JSONStream* stream, bool ref) const {
+  Object::PrintJSONImpl(stream, ref);
+}
+
+
 void ICData::PrintJSONImpl(JSONStream* stream, bool ref) const {
   JSONObject jsobj(stream);
   AddCommonObjectProperties(&jsobj, "Object", ref);