Do not allow non-configurable global properties to be made configurable (fixe...

src/runtime.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 1086 matching lines @@
     }
 
     // Safari does not allow the invocation of callback setters for
     // function declarations. To mimic this behavior, we do not allow
     // the invocation of setters for function values. This makes a
     // difference for global functions with the same names as event
     // handlers such as "function onload() {}". Firefox does call the
     // onload setter in those case and Safari does not. We follow
     // Safari for compatibility.
     if (value->IsJSFunction()) {
+      // Do not change DONT_DELETE to false from true.
+      if (lookup.IsProperty() &&
+          (lookup.type() != INTERCEPTOR)) {
+        attributes = static_cast<PropertyAttributes>(
+            attributes | (lookup.GetAttributes() & DONT_DELETE));
+      }
       RETURN_IF_EMPTY_HANDLE(SetLocalPropertyIgnoreAttributes(global,
                                                               name,
                                                               value,
                                                               attributes));
     } else {
       RETURN_IF_EMPTY_HANDLE(SetProperty(global, name, value, attributes));
     }
   }
 
   ASSERT(!Top::has_pending_exception());
@@ skipping 10179 matching lines @@
   } else {
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     Counters::gc_last_resort_from_js.Increment();
     Heap::CollectAllGarbage(false);
   }
 }
 
 
 } }  // namespace v8::internal