Strict Mode assignment to read only property.

src/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 818 matching lines @@
                                       NULL);
 
   // Use the debugger context.
   SaveContext save;
   Top::set_context(*context);
 
   // Expose the builtins object in the debugger context.
   Handle<String> key = Factory::LookupAsciiSymbol("builtins");
   Handle<GlobalObject> global = Handle<GlobalObject>(context->global());
   RETURN_IF_EMPTY_HANDLE_VALUE(
-      SetProperty(global, key, Handle<Object>(global->builtins()), NONE),
+      SetProperty(global, key, Handle<Object>(global->builtins()),
+                  NONE, kNonStrictMode),
       false);
 
   // Compile the JavaScript for the debugger in the debugger context.
   Debugger::set_compiling_natives(true);
   bool caught_exception =
       !CompileDebuggerScript(Natives::GetIndex("mirror")) ||
       !CompileDebuggerScript(Natives::GetIndex("debug"));
 
   if (FLAG_enable_liveedit) {
     caught_exception = caught_exception ||
@@ skipping 2225 matching lines @@
     {
       Locker locker;
       Debugger::CallMessageDispatchHandler();
     }
   }
 }
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 } }  // namespace v8::internal