Fix the linux build.

runtime/vm/custom_isolate_test.cc

 // Copyright (c) 2011, 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 "include/dart_api.h"
 
 #include "vm/unit_test.h"
 
 // Custom Isolate Test.
 //
@@ skipping 260 matching lines @@
 
 static bool PostMessage(Dart_Isolate dest_isolate,
                         Dart_Port dest_port,
                         Dart_Port reply_port,
                         Dart_Message message) {
   OS::Print("-- Posting message dest(%d) reply(%d) --\n",
             dest_port, reply_port);
   OS::Print("-- Adding MessageEvent to queue --\n");
   event_queue->Add(
       new MessageEvent(dest_isolate, dest_port, reply_port, message));
+  return true;
 }
 
 
 static void ClosePort(Dart_Isolate isolate,
                       Dart_Port port) {
   OS::Print("-- Closing port (%lld) for isolate(%p) --\n",
             port, isolate);
 
   // Remove any pending events for the isolate/port.
   event_queue->ClosePort(isolate, port);
@@ skipping 40 matching lines @@
     free(const_cast<char*>(saved_echo));
   }
   saved_echo = strdup(c_str);
   OS::Print("-- (isolate=%p) %s\n", Dart_CurrentIsolate(), c_str);
   Dart_ExitScope();
 }
 
 
 static void CustomIsolateImpl_start(Dart_NativeArguments args) {
   OS::Print("-- Enter: CustomIsolateImpl_start --\n");
-  Dart_Handle result;
 
   // We would probably want to pass in the this pointer too, so we
   // could associate the CustomIsolateImpl instance with the
   // Dart_Isolate by storing it in a native field.
   EXPECT_EQ(1, Dart_GetNativeArgumentCount(args));
   Dart_Handle param = Dart_GetNativeArgument(args, 0);
   EXPECT_VALID(param);
   EXPECT(Dart_IsString(param));
   const char* isolate_main = NULL;
   EXPECT_VALID(Dart_StringToCString(param, &isolate_main));
@@ skipping 22 matching lines @@
 
   OS::Print("-- Exit: CustomIsolateImpl_start --\n");
   Dart_ExitScope();
 }
 
 
 UNIT_TEST_CASE(CustomIsolates) {
   event_queue = new EventQueue();
   current_event = NULL;
 
-  Dart_Isolate main_isolate = Dart_CreateIsolate(NULL, NULL);
+  Dart_CreateIsolate(NULL, NULL);
   Dart_SetMessageCallbacks(&PostMessage, &ClosePort);
   Dart_EnterScope();
   Dart_Handle result;
 
   // Create a test library.
   Dart_Handle lib = TestCase::LoadTestScript(kCustomIsolateScriptChars,
                                              NativeLookup);
   EXPECT_VALID(lib);
 
   // Run main.
@@ skipping 23 matching lines @@
   OS::Print("-- Finished event loop --\n");
   EXPECT_STREQ("Received: 43", saved_echo);
   free(const_cast<char*>(saved_echo));
 
   delete event_queue;
 }
 
 #endif  // TARGET_ARCH_IA32.
 
 }  // namespace dart