Make stdin blocking when using Stdin::readByte and readLine.

runtime/bin/stdin_macos.cc

 // Copyright (c) 2013, 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 <termios.h>  // NOLINT
 
 #include "bin/stdin.h"
+#include "bin/fdutils.h"
 
 
 namespace dart {
 namespace bin {
 
 int Stdin::ReadByte() {
+  FDUtils::SetBlocking(fileno(stdin));
   int c = getchar();
   if (c == EOF) {
     c = -1;
   }
+  FDUtils::SetNonBlocking(fileno(stdin));
   return c;
 }
 
 
 void Stdin::SetEchoMode(bool enabled) {
   struct termios term;
   tcgetattr(fileno(stdin), &term);
   if (enabled) {
     term.c_lflag |= ECHO|ECHONL;
   } else {
@@ skipping 12 matching lines @@
     term.c_lflag &= ~(ICANON);
   }
   tcsetattr(fileno(stdin), TCSANOW, &term);
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_MACOS)