Implement implicit instance checks for API accessors.

src/objects-debug.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 666 matching lines @@
 }
 
 
 void AccessorInfo::AccessorInfoVerify() {
   CHECK(IsAccessorInfo());
   VerifyPointer(getter());
   VerifyPointer(setter());
   VerifyPointer(name());
   VerifyPointer(data());
   VerifyPointer(flag());
+  VerifyPointer(expected_receiver_type());
 }
 
 
 void AccessorPair::AccessorPairVerify() {
   CHECK(IsAccessorPair());
   VerifyPointer(getter());
   VerifyPointer(setter());
 }
 
 
@@ skipping 331 matching lines @@
   FixedArray* proto_transitions = prototype_transitions();
   MemsetPointer(proto_transitions->data_start(),
                 GetHeap()->the_hole_value(),
                 proto_transitions->length());
 }
 
 
 #endif  // DEBUG
 
 } }  // namespace v8::internal