Improve the encoding/decoding to/from system encoding on Windows

runtime/bin/platform_win.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_WINDOWS)
 
 #include "bin/file.h"
 #include "bin/platform.h"
 #include "bin/log.h"
 #include "bin/socket.h"
 #include "bin/utils.h"
+#include "bin/utils_win.h"
 
 
 namespace dart {
 namespace bin {
 
 bool Platform::Initialize() {
   // Nothing to do on Windows.
   return true;
 }
 
@@ skipping 36 matching lines @@
     // variables like %=C:% and %=ExitCode%, and the Dart environment does
     // not include these.
     if (*tmp != '=') i++;
     tmp += (wcslen(tmp) + 1);
   }
   *count = i;
   char** result = new char*[i];
   tmp = strings;
   for (intptr_t current = 0; current < i;) {
     // Skip the strings that were not counted above.
-    if (*tmp != '=') result[current++] = StringUtils::WideToUtf8(tmp);
+    if (*tmp != '=') result[current++] = StringUtilsWin::WideToUtf8(tmp);
     tmp += (wcslen(tmp) + 1);
   }
   FreeEnvironmentStringsW(strings);
   return result;
 }
 
 
 void Platform::FreeEnvironment(char** env, intptr_t count) {
   for (intptr_t i = 0; i < count; i++) {
     free(env[i]);
   }
   delete[] env;
 }
 
 
 char* Platform::ResolveExecutablePath() {
   // GetModuleFileNameW cannot directly provide information on the
   // required buffer size, so start out with a buffer large enough to
   // hold any Windows path.
   const int kTmpBufferSize = 32768;
   wchar_t* tmp_buffer = reinterpret_cast<wchar_t*>(malloc(kTmpBufferSize));
   // Ensure no last error before calling GetModuleFileNameW.
   SetLastError(ERROR_SUCCESS);
   // Get the required length of the buffer.
   int path_length = GetModuleFileNameW(NULL, tmp_buffer, kTmpBufferSize);
   if (GetLastError() != ERROR_SUCCESS) {
     free(tmp_buffer);
     return NULL;
   }
-  char* path = StringUtils::WideToUtf8(tmp_buffer);
+  char* path = StringUtilsWin::WideToUtf8(tmp_buffer);
   free(tmp_buffer);
   // Return the canonical path as the returned path might contain symlinks.
   char* canon_path = File::GetCanonicalPath(path);
   free(path);
   return canon_path;
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_WINDOWS)