A64: Fix int32 use in Lithium string functions

src/a64/code-stubs-a64.cc

 // Copyright 2013 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 3522 matching lines @@
   __ Bind(&got_smi_index_);
   // Check for index out of range.
   __ Ldrsw(result_, UntagSmiFieldMemOperand(object_, String::kLengthOffset));
   __ Cmp(result_, Operand::UntagSmi(index_));
   __ B(ls, index_out_of_range_);
 
   __ SmiUntag(index_);
 
   StringCharLoadGenerator::Generate(masm,
                                     object_,
-                                    index_,
+                                    index_.W(),
                                     result_,
                                     &call_runtime_);
   __ SmiTag(result_);
   __ Bind(&exit_);
 }
 
 
 void StringCharCodeAtGenerator::GenerateSlow(
     MacroAssembler* masm,
     const RuntimeCallHelper& call_helper) {
@@ skipping 2245 matching lines @@
                               MemOperand(fp, 6 * kPointerSize),
                               NULL);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_A64