Don't do a second lookup as we have it already.

src/ic.cc

 // Copyright 2006-2009 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 310 matching lines @@
       return ReferenceError("not_defined", name);
     }
     return TypeError("undefined_method", object, name);
   }
 
   // Lookup is valid: Update inline cache and stub cache.
   if (FLAG_use_ic && lookup.IsLoaded()) {
     UpdateCaches(&lookup, state, object, name);
   }
 
+  // Get the property.
+  PropertyAttributes attr;
+  result = object->GetProperty(*object, &lookup, *name, &attr);
+  if (result->IsFailure()) return result;
   if (lookup.type() == INTERCEPTOR) {
-    // Get the property.
-    PropertyAttributes attr;
-    result = object->GetProperty(*name, &attr);
-    if (result->IsFailure()) return result;
     // If the object does not have the requested property, check which
     // exception we need to throw.
     if (attr == ABSENT) {
       if (is_contextual()) {
         return ReferenceError("not_defined", name);
       }
       return TypeError("undefined_method", object, name);
     }
-  } else {
-    // Lookup is valid and no interceptors are involved. Get the
-    // property.
-    result = object->GetProperty(*name);
-    if (result->IsFailure()) return result;
   }
 
   ASSERT(result != Heap::the_hole_value());
 
   if (result->IsJSFunction()) {
     // Check if there is an optimized (builtin) version of the function.
     // Ignored this will degrade performance for Array.prototype.{push,pop}.
     // Please note we only return the optimized function iff
     // the JSObject has FastElements.
     if (object->IsJSObject() && JSObject::cast(*object)->HasFastElements()) {
@@ skipping 964 matching lines @@
 #undef ADDR
 };
 
 
 Address IC::AddressFromUtilityId(IC::UtilityId id) {
   return IC_utilities[id];
 }
 
 
 } }  // namespace v8::internal