Fix a few clang warnings (which -Werror treats as errors)

src/ia32/lithium-codegen-ia32.cc

 // Copyright 2011 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 3157 matching lines @@
                         times_pointer_size,
                         FixedArray::kHeaderSize));
     __ RecordWrite(elements, key, value);
   }
 }
 
 
 void LCodeGen::DoStoreKeyedFastDoubleElement(
     LStoreKeyedFastDoubleElement* instr) {
   XMMRegister value = ToDoubleRegister(instr->value());
-  Register key = instr->key()->IsRegister() ? ToRegister(instr->key()) : no_reg;
   Label have_value;
 
   __ ucomisd(value, value);
   __ j(parity_odd, &have_value);  // NaN.
 
   ExternalReference canonical_nan_reference =
       ExternalReference::address_of_canonical_non_hole_nan();
   __ movdbl(value, Operand::StaticVariable(canonical_nan_reference));
   __ bind(&have_value);
 
@@ skipping 1189 matching lines @@
                                          env->deoptimization_index());
   __ InvokeBuiltin(Builtins::IN, CALL_FUNCTION, safepoint_generator);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32