Thread pool changes

runtime/bin/thread_pool.cc

Index: runtime/bin/thread_pool.cc
diff --git a/runtime/bin/thread_pool.cc b/runtime/bin/thread_pool.cc
index 2a974e92d0d9bfa9bbb544e4d3cc277a114560ec..20317fdf6bb64ba7a1f80aea37fa813323b3bf45 100644
--- a/runtime/bin/thread_pool.cc
+++ b/runtime/bin/thread_pool.cc
@@ -18,7 +18,7 @@ void ThreadPool::InsertTask(Task task) {
 Task ThreadPool::WaitForTask() {
   TaskQueueEntry* entry = queue.Remove();
   if (entry == NULL) {
-    return -1;
+    return NULL;
   }
   Task task = entry->task();
   delete entry;
@@ -36,9 +36,7 @@ void* ThreadPool::Main(void* args) {
       printf("Waiting for task\n");
     }
     Task task = pool->WaitForTask();
-    if (Dart_IsVMFlagSet("trace_thread_pool")) {
-      printf("Got task %d\n", task);
-    }
+    (*(pool->task_handler_))(task);
   }
   return NULL;
 };