Fix same Windows compiler error in another place.

src/ia32/codegen-ia32.cc

 // Copyright 2006-2009 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 2173 matching lines @@
       left_side = Result(left_reg);
       right_side = Result(right_val);
       Result temp2 = allocator_->Allocate();
       ASSERT(temp2.is_valid());
       // Test string equality and comparison.
       if (cc == equal) {
         Label comparison_done;
         __ cmp(FieldOperand(left_side.reg(), String::kLengthOffset),
                Immediate(1));
         __ j(not_equal, &comparison_done);
+        uint8_t char_value =
+            static_cast<uint8_t>(String::cast(*right_side.handle())->Get(0));
         __ cmpb(FieldOperand(left_side.reg(), SeqAsciiString::kHeaderSize),
-                String::cast(*right_side.handle())->Get(0));
+                char_value);
         __ bind(&comparison_done);
       } else {
         __ mov(temp2.reg(),
                FieldOperand(left_side.reg(), String::kLengthOffset));
         __ sub(Operand(temp2.reg()), Immediate(1));
         Label comparison;
         // If the length is 0 then our subtraction gave -1 which compares less
         // than any character.
         __ j(negative, &comparison);
         // Otherwise load the first character.
@@ skipping 7559 matching lines @@
 
   // Call the runtime; it returns -1 (less), 0 (equal), or 1 (greater)
   // tagged as a small integer.
   __ bind(&runtime);
   __ TailCallRuntime(ExternalReference(Runtime::kStringCompare), 2, 1);
 }
 
 #undef __
 
 } }  // namespace v8::internal