Start adding vm/cc tests for rewind functionality.

runtime/vm/service.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/service.h"
 
 #include "include/dart_api.h"
 #include "include/dart_native_api.h"
 #include "platform/globals.h"
 
@@ skipping 822 matching lines @@
     method_name ^= msg.At(3);
     param_keys ^= msg.At(4);
     param_values ^= msg.At(5);
 
     ASSERT(!method_name.IsNull());
     ASSERT(seq.IsNull() || seq.IsString() || seq.IsNumber());
     ASSERT(!param_keys.IsNull());
     ASSERT(!param_values.IsNull());
     ASSERT(param_keys.Length() == param_values.Length());
 
-    if (!reply_port.IsSendPort()) {
+    // We expect a reply port unless there is a null sequence id,
+    // which indicates that no reply should be sent.  We use this in
+    // tests.
+    if (!seq.IsNull() && !reply_port.IsSendPort()) {
       FATAL("SendPort expected.");
     }
 
     JSONStream js;
-    js.Setup(zone.GetZone(), SendPort::Cast(reply_port).Id(), seq, method_name,
-             param_keys, param_values, parameters_are_dart_objects);
+    Dart_Port reply_port_id =
+        (reply_port.IsNull() ? ILLEGAL_PORT : SendPort::Cast(reply_port).Id());
+    js.Setup(zone.GetZone(), reply_port_id, seq, method_name, param_keys,
+             param_values, parameters_are_dart_objects);
 
     // RPC came in with a custom service id zone.
     const char* id_zone_param = js.LookupParam("_idZone");
 
     if (id_zone_param != NULL) {
       // Override id zone.
       if (strcmp("default", id_zone_param) == 0) {
         // Ring with eager id allocation. This is the default ring and default
         // policy.
         // Nothing to do.
@@ skipping 3262 matching lines @@
     if (strcmp(method_name, method.name) == 0) {
       return &method;
     }
   }
   return NULL;
 }
 
 #endif  // !PRODUCT
 
 }  // namespace dart