A MessageObject is a purely internal object to hold information about

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index 96d07a859b296b5223d7355f56d1fbb591535b17..d55a201e595d773951f0903beed1bb66e74d2b54 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -10748,6 +10748,45 @@ static MaybeObject* Runtime_GetFromCache(Arguments args) {
   return *value;
 }
 
+
+static MaybeObject* Runtime_NewMessageObject(Arguments args) {
+  HandleScope scope;
+  CONVERT_ARG_CHECKED(String, type, 0);
+  CONVERT_ARG_CHECKED(JSArray, arguments, 1);
+  return *Factory::NewJSMessageObject(type,
+                                      arguments,
+                                      0,
+                                      0,
+                                      Factory::undefined_value(),
+                                      Factory::undefined_value(),
+                                      Factory::undefined_value());
+}
+
+
+static MaybeObject* Runtime_MessageGetType(Arguments args) {
+  CONVERT_CHECKED(JSMessageObject, message, args[0]);
+  return message->type();
+}
+
+
+static MaybeObject* Runtime_MessageGetArguments(Arguments args) {
+  CONVERT_CHECKED(JSMessageObject, message, args[0]);
+  return message->arguments();
+}
+
+
+static MaybeObject* Runtime_MessageGetStartPosition(Arguments args) {
+  CONVERT_CHECKED(JSMessageObject, message, args[0]);
+  return Smi::FromInt(message->start_position());
+}
+
+
+static MaybeObject* Runtime_MessageGetScript(Arguments args) {
+  CONVERT_CHECKED(JSMessageObject, message, args[0]);
+  return message->script();
+}
+
+
 #ifdef DEBUG
 // ListNatives is ONLY used by the fuzz-natives.js in debug mode
 // Exclude the code in release mode.