Fix developer shell build on Windows

src/d8-posix.cc

 // Copyright 2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 520 matching lines @@
     const char* message = "os.chdir(): String conversion of argument failed.";
     return ThrowException(String::New(message));
   }
   if (chdir(*directory) != 0) {
     return ThrowException(String::New(strerror(errno)));
   }
   return v8::Undefined();
 }
 
 
+Handle<Value> Shell::SetEnvironment(const Arguments& args) {
+  if (args.Length() != 2) {
+    const char* message = "setenv() takes two arguments";
+    return ThrowException(String::New(message));
+  }
+  String::Utf8Value var(args[0]);
+  String::Utf8Value value(args[1]);
+  if (*var == NULL) {
+    const char* message =
+        "os.setenv(): String conversion of variable name failed.";
+    return ThrowException(String::New(message));
+  }
+  if (*value == NULL) {
+    const char* message =
+        "os.setenv(): String conversion of variable contents failed.";
+    return ThrowException(String::New(message));
+  }
+  setenv(*var, *value, 1);
+  return v8::Undefined();
+}
+
+
 }  // namespace v8