Really remove io support when dart:io is unsupported.

runtime/bin/platform_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 "bin/platform.h"
+
 #if !TARGET_OS_IOS
 #include <crt_externs.h>  // NOLINT
 #endif  // !TARGET_OS_IOS
 #include <mach-o/dyld.h>
 #include <signal.h>  // NOLINT
 #include <string.h>  // NOLINT
 #include <sys/sysctl.h>  // NOLINT
 #include <sys/types.h>  // NOLINT
 #include <unistd.h>  // NOLINT
 
 #include "bin/fdutils.h"
 #include "bin/file.h"
-#include "bin/platform.h"
 
 namespace dart {
 namespace bin {
 
+const char* Platform::executable_name_ = NULL;
+char* Platform::resolved_executable_name_ = NULL;
+int Platform::script_index_ = 1;
+char** Platform::argv_ = NULL;
+
 bool Platform::Initialize() {
   // Turn off the signal handler for SIGPIPE as it causes the process
   // to terminate on writing to a closed pipe. Without the signal
   // handler error EPIPE is set instead.
   struct sigaction act;
   bzero(&act, sizeof(act));
   act.sa_handler = SIG_IGN;
   if (sigaction(SIGPIPE, &act, 0) != 0) {
     perror("Setting signal handler failed");
     return false;
@@ skipping 83 matching lines @@
 
 
 void Platform::Exit(int exit_code) {
   exit(exit_code);
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_MACOS)