[dart:io] Move Platform.ansiSupported to {Stdin,Stdout}.supportsAnsiEscapes

runtime/bin/platform.h

 // 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.
 
 #ifndef RUNTIME_BIN_PLATFORM_H_
 #define RUNTIME_BIN_PLATFORM_H_
 
 #include "bin/builtin.h"
 #include "platform/globals.h"
 
@@ skipping 65 matching lines @@
   }
 
   // Stores and gets the flags passed to the executable.
   static void SetExecutableArguments(int script_index, char** argv) {
     script_index_ = script_index;
     argv_ = argv;
   }
   static int GetScriptIndex() { return script_index_; }
   static char** GetArgv() { return argv_; }
 
-  static bool AnsiSupported();
-
   static DART_NORETURN void Exit(int exit_code);
 
  private:
   // The path to the executable.
   static const char* executable_name_;
   // The path to the resolved executable.
   static char* resolved_executable_name_;
 
   static int script_index_;
   static char** argv_;  // VM flags are argv_[1 ... script_index_ - 1]
 
   DISALLOW_ALLOCATION();
   DISALLOW_IMPLICIT_CONSTRUCTORS(Platform);
 };
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // RUNTIME_BIN_PLATFORM_H_