Consistently make the bounds check for AccessArgumentsAt explicit.

src/ia32/lithium-codegen-ia32.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 2724 matching lines @@
   __ mov(result, FieldOperand(input,
                               ExternalArray::kExternalPointerOffset));
 }
 
 
 void LCodeGen::DoAccessArgumentsAt(LAccessArgumentsAt* instr) {
   Register arguments = ToRegister(instr->arguments());
   Register length = ToRegister(instr->length());
   Operand index = ToOperand(instr->index());
   Register result = ToRegister(instr->result());
-
-  __ sub(length, index);
-  DeoptimizeIf(below_equal, instr->environment());
-
   // There are two words between the frame pointer and the last argument.
   // Subtracting from length accounts for one of them add one more.
+  __ sub(length, index);
   __ mov(result, Operand(arguments, length, times_4, kPointerSize));
 }
 
 
 void LCodeGen::DoLoadKeyedFastElement(LLoadKeyedFastElement* instr) {
   Register result = ToRegister(instr->result());
 
   // Load the result.
   __ mov(result,
          BuildFastArrayOperand(instr->elements(),
@@ skipping 2779 matching lines @@
                               FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32