Add os.chdir and os.setenv to d8. Move system() to os.system().

src/d8.h

 // 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 112 matching lines @@
   static Handle<Array> GetCompletions(Handle<String> text,
                                       Handle<String> full);
   static Handle<Object> DebugMessageDetails(Handle<String> message);
   static Handle<Value> DebugCommandToJSONRequest(Handle<String> command);
 
   static Handle<Value> Print(const Arguments& args);
   static Handle<Value> Yield(const Arguments& args);
   static Handle<Value> Quit(const Arguments& args);
   static Handle<Value> Version(const Arguments& args);
   static Handle<Value> Load(const Arguments& args);
-  // system("program_name", ["arg1", "arg2", ...], timeout1, timeout2) will run
-  // the command, passing the arguments to the program.  The standard output of
-  // the program will be picked up and returned as a multiline string.  If
+  // The OS object on the global object contains methods for performing
+  // operating system calls:
+  //
+  // os.system("program_name", ["arg1", "arg2", ...], timeout1, timeout2) will
+  // run the command, passing the arguments to the program.  The standard output
+  // of the program will be picked up and returned as a multiline string.  If
   // timeout1 is present then it should be a number.  -1 indicates no timeout
   // and a positive number is used as a timeout in milliseconds that limits the
   // time spent waiting between receiving output characters from the program.
   // timeout2, if present, should be a number indicating the limit in
   // milliseconds on the total running time of the program.  Exceptions are
   // thrown on timeouts or other errors or if the exit status of the program
   // indicates an error.
+  //
+  // os.chdir(dir) changes directory to the given directory.  Throws an
+  // exception/ on error.
+  //
+  // os.setenv(variable, value) sets an environment variable.  Repeated calls to
+  // this method leak memory due to the API of setenv in the standard C library.
+  static Handle<Value> OSObject(const Arguments& args);
   static Handle<Value> System(const Arguments& args);
+  static Handle<Value> ChangeDirectory(const Arguments& args);
+  static Handle<Value> SetEnvironment(const Arguments& args);
 
   static Handle<Context> utility_context() { return utility_context_; }
 
   static const char* kHistoryFileName;
   static const char* kPrompt;
  private:
   static Persistent<Context> utility_context_;
   static Persistent<Context> evaluation_context_;
   static CounterMap* counter_map_;
   // We statically allocate a set of local counters to be used if we
@@ skipping 22 matching lines @@
   const char* name_;
   LineEditor* next_;
   static LineEditor* first_;
 };
 
 
 }  // namespace v8
 
 
 #endif  // V8_D8_H_