Let debug target pick the debugger port

runtime/bin/dbg_connection_macos.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 "platform/globals.h"
 #if defined(TARGET_OS_MACOS)
 
 #include <errno.h>  // NOLINT
 #include <stdio.h>  // NOLINT
 #include <stdlib.h>  // NOLINT
@@ skipping 139 matching lines @@
   status = TEMP_FAILURE_RETRY(kevent(kqueue_fd_, &event, 1, NULL, 0, NULL));
   if (status == -1) {
     FATAL1("Failed adding listener socket to kqueue: %s\n", strerror(errno));
   }
 }
 
 
 void DebuggerConnectionImpl::StartHandler(int port_number) {
   ASSERT(DebuggerConnectionHandler::listener_fd_ != -1);
   SetupPollQueue();
-  int result =
-      dart::Thread::Start(&DebuggerConnectionImpl::Handler, 0);
+  int result = dart::Thread::Start(&DebuggerConnectionImpl::Handler, 0);
   if (result != 0) {
     FATAL1("Failed to start debugger connection handler thread: %d\n", result);
   }
 }
 
 
 intptr_t DebuggerConnectionImpl::Send(intptr_t socket,
                                       const char* buf,
                                       int len) {
   return TEMP_FAILURE_RETRY(write(socket, buf, len));
 }
 
 
 intptr_t DebuggerConnectionImpl::Receive(intptr_t socket, char* buf, int len) {
   return TEMP_FAILURE_RETRY(read(socket, buf, len));
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_MACOS)