Omit variables beginning with "=" from Windows environment.

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/platform.h"
 #include "bin/log.h"
 #include "bin/socket.h"
@@ skipping 26 matching lines @@
   return gethostname(buffer, buffer_length) == 0;
 }
 
 
 char** Platform::Environment(intptr_t* count) {
   wchar_t* strings = GetEnvironmentStringsW();
   if (strings == NULL) return NULL;
   wchar_t* tmp = strings;
   intptr_t i = 0;
   while (*tmp != '\0') {
-    i++;
+    // Skip environment strings starting with "=".
+    // These are synthetic variables corresponding to dynamic environment
+    // 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; current++) {
-    result[current] = StringUtils::WideToUtf8(tmp);
+  for (intptr_t current = 0; current < i;) {
+    // Skip the strings that were not counted above.
+    if (*tmp != '=') result[current++] = StringUtils::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;
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_WINDOWS)