Another fix for non-mac build:

runtime/vm/thread_pool_test.cc

 // Copyright (c) 2012, 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/os.h"
 #include "vm/thread.h"
 #include "vm/thread_pool.h"
 #include "vm/unit_test.h"
 
 namespace dart {
@@ skipping 43 matching lines @@
   thread_pool.Run(new TestTask(&sync, &done));
   {
     MonitorLocker ml(&sync);
     while (!done) {
       ml.Wait();
     }
   }
   EXPECT(done);
 
   // Do a sanity test on the worker stats.
-  EXPECT_EQ(1, thread_pool.workers_started());
-  EXPECT_EQ(0, thread_pool.workers_stopped());
-  EXPECT_EQ(1, thread_pool.workers_idle());
-  EXPECT_EQ(0, thread_pool.workers_running());
+  EXPECT_EQ(1U, thread_pool.workers_started());
+  EXPECT_EQ(0U, thread_pool.workers_stopped());
+  EXPECT_EQ(1U, thread_pool.workers_idle());
+  EXPECT_EQ(0U, thread_pool.workers_running());
 }
 
 
 UNIT_TEST_CASE(ThreadPool_RunMany) {
   const int kTaskCount = 100;
   ThreadPool thread_pool;
   Monitor sync[kTaskCount];
   bool done[kTaskCount];
 
   for (int i = 0; i < kTaskCount; i++) {
@@ skipping 48 matching lines @@
   EXPECT_EQ(1, exit_count);
 }
 
 
 UNIT_TEST_CASE(ThreadPool_WorkerTimeout) {
   // Adjust the worker timeout so that we timeout quickly.
   int saved_timeout = FLAG_worker_timeout_millis;
   FLAG_worker_timeout_millis = 1;
 
   ThreadPool thread_pool;
-  EXPECT_EQ(0, thread_pool.workers_started());
-  EXPECT_EQ(0, thread_pool.workers_stopped());
+  EXPECT_EQ(0U, thread_pool.workers_started());
+  EXPECT_EQ(0U, thread_pool.workers_stopped());
 
   // Run a worker.
   Monitor sync;
   bool done = false;
   thread_pool.Run(new TestTask(&sync, &done));
-  EXPECT_EQ(1, thread_pool.workers_started());
-  EXPECT_EQ(0, thread_pool.workers_stopped());
+  EXPECT_EQ(1U, thread_pool.workers_started());
+  EXPECT_EQ(0U, thread_pool.workers_stopped());
   {
     MonitorLocker ml(&sync);
     while (!done) {
       ml.Wait();
     }
   }
   EXPECT(done);
 
   // Wait up to 5 seconds to see if a worker times out.
   const int kMaxWait = 5000;
   int waited = 0;
   while (thread_pool.workers_stopped() == 0 && waited < kMaxWait) {
     OS::Sleep(1);
     waited += 1;
   }
-  EXPECT_EQ(1, thread_pool.workers_stopped());
+  EXPECT_EQ(1U, thread_pool.workers_stopped());
   FLAG_worker_timeout_millis = saved_timeout;
 }
 
 
 class SpawnTask : public ThreadPool::Task {
  public:
   SpawnTask(ThreadPool* pool, Monitor* sync, int todo, int total, int* done)
       : pool_(pool), sync_(sync), todo_(todo), total_(total), done_(done) {
   }
 
@@ skipping 40 matching lines @@
     MonitorLocker ml(&sync);
     while (done < kTotalTasks) {
       ml.Wait();
     }
   }
   EXPECT_EQ(kTotalTasks, done);
 }
 
 
 }  // namespace dart