[Arguments] Support deletion of arguments properties.

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 10763 matching lines @@
 
   if (sinfo->number_of_context_slots() > Context::MIN_CONTEXT_SLOTS) {
     index = scope_info->ContextSlotIndex(isolate->heap()->arguments_symbol(),
                                          NULL);
     if (index != -1) {
       return Handle<Object>(function_context->get(index), isolate);
     }
   }
 
   const int length = frame->ComputeParametersCount();
-  UNIMPLEMENTED();
   Handle<JSObject> arguments =
       isolate->factory()->NewArgumentsObject(function, length);
   Handle<FixedArray> array = isolate->factory()->NewFixedArray(length);
 
   AssertNoAllocation no_gc;
   WriteBarrierMode mode = array->GetWriteBarrierMode(no_gc);
   for (int i = 0; i < length; i++) {
     array->set(i, frame->GetParameter(i), mode);
   }
   arguments->set_elements(*array);
@@ skipping 1503 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