[d8] Remove "os" object from d8.

src/d8.h

Index: src/d8.h
diff --git a/src/d8.h b/src/d8.h
index 16f612c97ad47b981fbec6b35a60ff4039d04773..d12334ed9bdb13a79d00a3fb8862a19154ce8323 100644
--- a/src/d8.h
+++ b/src/d8.h
@@ -401,42 +401,6 @@ class Shell : public i::AllStatic {
       const v8::FunctionCallbackInfo<v8::Value>& args);
   static void WorkerGetMessage(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void WorkerTerminate(const v8::FunctionCallbackInfo<v8::Value>& args);
-  // 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.
-  //
-  // os.umask(alue) calls the umask system call and returns the old umask.
-  //
-  // os.mkdirp(name, mask) creates a directory.  The mask (if present) is anded
-  // with the current umask.  Intermediate directories are created if necessary.
-  // An exception is not thrown if the directory already exists.  Analogous to
-  // the "mkdir -p" command.
-  static void System(const v8::FunctionCallbackInfo<v8::Value>& args);
-  static void ChangeDirectory(const v8::FunctionCallbackInfo<v8::Value>& args);
-  static void SetEnvironment(const v8::FunctionCallbackInfo<v8::Value>& args);
-  static void UnsetEnvironment(const v8::FunctionCallbackInfo<v8::Value>& args);
-  static void SetUMask(const v8::FunctionCallbackInfo<v8::Value>& args);
-  static void MakeDirectory(const v8::FunctionCallbackInfo<v8::Value>& args);
-  static void RemoveDirectory(const v8::FunctionCallbackInfo<v8::Value>& args);
-
-  static void AddOSMethods(v8::Isolate* isolate,
-                           Local<ObjectTemplate> os_template);
 
   static const char* kPrompt;
   static ShellOptions options;