Don't use global variables for capturing stdio.

runtime/bin/builtin_natives.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 <stdlib.h>
 #include <stdio.h>
 #include <string.h>
 
 #include "include/dart_api.h"
 #include "include/dart_tools_api.h"
 
 #include "platform/assert.h"
 
 #include "bin/builtin.h"
 #include "bin/dartutils.h"
+#include "bin/file.h"
 #include "bin/io_natives.h"
 #include "bin/platform.h"
 
 namespace dart {
 namespace bin {
 
 // Lists the native functions implementing basic functionality in
 // standalone dart, such as printing, file I/O, and platform information.
 // Advanced I/O classes like sockets and process management are implemented
 // using functions listed in io_natives.cc.
@@ skipping 46 matching lines @@
   for (int i = 0; i < num_entries; i++) {
     struct NativeEntries* entry = &(BuiltinEntries[i]);
     if (reinterpret_cast<Dart_NativeFunction>(entry->function_) == nf) {
       return reinterpret_cast<const uint8_t*>(entry->name_);
     }
   }
   return IONativeSymbol(nf);
 }
 
 
-extern bool capture_stdout;
-
-
 // Implementation of native functions which are used for some
 // test/debug functionality in standalone dart mode.
 void FUNCTION_NAME(Builtin_PrintString)(Dart_NativeArguments args) {
   intptr_t length = 0;
   uint8_t* chars = NULL;
   Dart_Handle str = Dart_GetNativeArgument(args, 0);
   Dart_Handle result = Dart_StringToUTF8(str, &chars, &length);
   if (Dart_IsError(result)) Dart_PropagateError(result);
 
   // Uses fwrite to support printing NUL bytes.
   fwrite(chars, 1, length, stdout);
   fputs("\n", stdout);
   fflush(stdout);
-  if (capture_stdout) {
+  if (File::capture_stdout()) {
     // For now we report print output on the Stdout stream.
     uint8_t newline[] = { '\n' };
     Dart_ServiceSendDataEvent("Stdout", "WriteEvent", chars, length);
     Dart_ServiceSendDataEvent("Stdout", "WriteEvent",
                               newline, sizeof(newline));
   }
 }
 
 }  // namespace bin
 }  // namespace dart