A MessageObject is a purely internal object to hold information about

src/factory.cc

Index: src/factory.cc
diff --git a/src/factory.cc b/src/factory.cc
index 2bc878cc4dab0a532fc72ddae785779c155689cc..a3d55921b67e679ad0f14aa39aac4836198a5306 100644
--- a/src/factory.cc
+++ b/src/factory.cc
@@ -755,6 +755,24 @@ Handle<SharedFunctionInfo> Factory::NewSharedFunctionInfo(
 }
 
 
+Handle<JSMessageObject> Factory::NewJSMessageObject(
+    Handle<String> type,
+    Handle<JSArray> arguments,
+    int start_position,
+    int end_position,
+    Handle<Object> script,
+    Handle<Object> stack_trace,
+    Handle<Object> stack_frames) {
+  CALL_HEAP_FUNCTION(Heap::AllocateJSMessageObject(*type,
+                                                   *arguments,
+                                                   start_position,
+                                                   end_position,
+                                                   *script,
+                                                   *stack_trace,
+                                                   *stack_frames),
+                     JSMessageObject);
+}
+
 Handle<SharedFunctionInfo> Factory::NewSharedFunctionInfo(Handle<String> name) {
   CALL_HEAP_FUNCTION(Heap::AllocateSharedFunctionInfo(*name),
                      SharedFunctionInfo);