[dart:io] Remove DART_IO_DISABLED

runtime/bin/stdio_android.cc

Index: runtime/bin/stdio_android.cc
diff --git a/runtime/bin/stdio_android.cc b/runtime/bin/stdio_android.cc
index d4a48cb82ed83f6dc2e6aeac96014a1e542b1fb1..44a7fe7ecdb1908d6e51c51405d366bb635795aa 100644
--- a/runtime/bin/stdio_android.cc
+++ b/runtime/bin/stdio_android.cc
@@ -2,8 +2,6 @@
 // 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.
 
-#if !defined(DART_IO_DISABLED)
-
 #include "platform/globals.h"
 #if defined(HOST_OS_ANDROID)
 
@@ -111,5 +109,3 @@ bool Stdout::AnsiSupported(intptr_t fd, bool* supported) {
 }  // namespace dart
 
 #endif  // defined(HOST_OS_ANDROID)
-
-#endif  // !defined(DART_IO_DISABLED)