First take on custom call generators.

src/objects-debug.cc

 // Copyright 2006-2008 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 771 matching lines @@
   PrintF("\n - this_property_assignments = ");
   this_property_assignments()->ShortPrint();
   PrintF("\n");
 }
 
 void SharedFunctionInfo::SharedFunctionInfoVerify() {
   CHECK(IsSharedFunctionInfo());
   VerifyObjectField(kNameOffset);
   VerifyObjectField(kCodeOffset);
   VerifyObjectField(kInstanceClassNameOffset);
-  VerifyObjectField(kExternalReferenceDataOffset);
+  VerifyObjectField(kFunctionDataOffset);
   VerifyObjectField(kScriptOffset);
   VerifyObjectField(kDebugInfoOffset);
 }
 
 
 void JSGlobalProxy::JSGlobalProxyPrint() {
   PrintF("global_proxy");
   JSObjectPrint();
   PrintF("context : ");
   context()->ShortPrint();
@@ skipping 525 matching lines @@
     }
     current = hash;
   }
   return true;
 }
 
 
 #endif  // DEBUG
 
 } }  // namespace v8::internal