Do not implicitly convert receivers for builtin functions when inspecting frames.

src/runtime.cc

 // Copyright 2012 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 11043 matching lines @@
   if (at_return) {
     details->set(details_index++, *return_value);
   }
 
   // Add the receiver (same as in function frame).
   // THIS MUST BE DONE LAST SINCE WE MIGHT ADVANCE
   // THE FRAME ITERATOR TO WRAP THE RECEIVER.
   Handle<Object> receiver(it.frame()->receiver(), isolate);
   if (!receiver->IsJSObject() &&
       shared->is_classic_mode() &&
-      !shared->native()) {
+      !function->IsBuiltin()) {
     // If the receiver is not a JSObject and the function is not a
     // builtin or strict-mode we have hit an optimization where a
     // value object is not converted into a wrapped JS objects. To
     // hide this optimization from the debugger, we wrap the receiver
     // by creating correct wrapper object based on the calling frame's
     // native context.
     it.Advance();
     Handle<Context> calling_frames_native_context(
         Context::cast(Context::cast(it.frame()->context())->native_context()));
+    ASSERT(!receiver->IsUndefined() && !receiver->IsNull());
     receiver =
         isolate->factory()->ToObject(receiver, calling_frames_native_context);
   }
   details->set(kFrameDetailsReceiverIndex, *receiver);
 
   ASSERT_EQ(details_size, details_index);
   return *isolate->factory()->NewJSArrayWithElements(details);
 }
 
 
@@ skipping 2911 matching lines @@
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags,
                                        "Runtime::PerformGC");
   }
 }
 
 
 } }  // namespace v8::internal