Follow jsc on not throwing when trying to add a property to a non-extensible object.

src/objects.h

 // 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 1673 matching lines @@
                                                PropertyAttributes attributes);
 
   // Add a property to a slow-case object.
   MUST_USE_RESULT MaybeObject* AddSlowProperty(String* name,
                                                Object* value,
                                                PropertyAttributes attributes);
 
   // Add a property to an object.
   MUST_USE_RESULT MaybeObject* AddProperty(String* name,
                                            Object* value,
-                                           PropertyAttributes attributes);
+                                           PropertyAttributes attributes,
+                                           StrictModeFlag strict_mode);
 
   // Convert the object to use the canonical dictionary
   // representation. If the object is expected to have additional properties
   // added this number can be indicated to have the backing store allocated to
   // an initial capacity for holding these properties.
   MUST_USE_RESULT MaybeObject* NormalizeProperties(
       PropertyNormalizationMode mode,
       int expected_additional_properties);
   MUST_USE_RESULT MaybeObject* NormalizeElements();
 
@@ skipping 4912 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_