Don't emit LDummyUse for ArgumentsObject.

src/hydrogen-instructions.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 491 matching lines @@
     default: return "";
   }
 }
 
 
 bool HValue::CanReplaceWithDummyUses() {
   return FLAG_unreachable_code_elimination &&
       !(block()->IsReachable() ||
         IsBlockEntry() ||
         IsControlInstruction() ||
+        IsArgumentsObject() ||
         IsCapturedObject() ||
         IsSimulate() ||
         IsEnterInlined() ||
         IsLeaveInlined());
 }
 
 
 bool HValue::IsInteger32Constant() {
   return IsConstant() && HConstant::cast(this)->HasInteger32Value();
 }
@@ skipping 4204 matching lines @@
       break;
     case kExternalMemory:
       stream->Add("[external-memory]");
       break;
   }
 
   stream->Add("@%d", offset());
 }
 
 } }  // namespace v8::internal