A MessageObject is a purely internal object to hold information about

src/objects-debug.cc

 // Copyright 2010 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 140 matching lines @@
       JSRegExp::cast(this)->JSRegExpVerify();
       break;
     case FILLER_TYPE:
       break;
     case PROXY_TYPE:
       Proxy::cast(this)->ProxyVerify();
       break;
     case SHARED_FUNCTION_INFO_TYPE:
       SharedFunctionInfo::cast(this)->SharedFunctionInfoVerify();
       break;
+    case JS_MESSAGE_OBJECT_TYPE:
+      JSMessageObject::cast(this)->JSMessageObjectVerify();
+      break;
 
 #define MAKE_STRUCT_CASE(NAME, Name, name) \
   case NAME##_TYPE:                        \
     Name::cast(this)->Name##Verify();      \
     break;
     STRUCT_LIST(MAKE_STRUCT_CASE)
 #undef MAKE_STRUCT_CASE
 
     default:
       UNREACHABLE();
@@ skipping 118 matching lines @@
 
 
 void JSValue::JSValueVerify() {
   Object* v = value();
   if (v->IsHeapObject()) {
     VerifyHeapPointer(v);
   }
 }
 
 
+void JSMessageObject::JSMessageObjectVerify() {
+  CHECK(IsJSMessageObject());
+  CHECK(type()->IsString());
+  CHECK(arguments()->IsJSArray());
+  VerifyObjectField(kStartPositionOffset);
+  VerifyObjectField(kEndPositionOffset);
+  VerifyObjectField(kArgumentsOffset);
+  VerifyObjectField(kScriptOffset);
+  VerifyObjectField(kStackTraceOffset);
+  VerifyObjectField(kStackFramesOffset);
+}
+
+
 void String::StringVerify() {
   CHECK(IsString());
   CHECK(length() >= 0 && length() <= Smi::kMaxValue);
   if (IsSymbol()) {
     CHECK(!Heap::InNewSpace(this));
   }
 }
 
 
 void JSFunction::JSFunctionVerify() {
@@ skipping 388 matching lines @@
         ASSERT(e->IsUndefined());
       }
     }
   }
 }
 
 
 #endif  // DEBUG
 
 } }  // namespace v8::internal