Fix compilation with latest Xcode toolchain.

src/ia32/lithium-ia32.h

 // 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 1831 matching lines @@
 
   int arity() const { return hydrogen()->argument_count() - 1; }
 };
 
 
 class LCallWithDescriptor V8_FINAL : public LTemplateResultInstruction<1> {
  public:
   LCallWithDescriptor(const CallInterfaceDescriptor* descriptor,
                       ZoneList<LOperand*>& operands,
                       Zone* zone)
-    : descriptor_(descriptor),
-      inputs_(descriptor->environment_length() + 1, zone) {
+    : inputs_(descriptor->environment_length() + 1, zone) {
     ASSERT(descriptor->environment_length() + 1 == operands.length());
     inputs_.AddAll(operands, zone);
   }
 
   LOperand* target() const { return inputs_[0]; }
 
  private:
   DECLARE_CONCRETE_INSTRUCTION(CallWithDescriptor, "call-with-descriptor")
   DECLARE_HYDROGEN_ACCESSOR(CallWithDescriptor)
 
   virtual void PrintDataTo(StringStream* stream) V8_OVERRIDE;
 
   int arity() const { return hydrogen()->argument_count() - 1; }
 
-  const CallInterfaceDescriptor* descriptor_;
   ZoneList<LOperand*> inputs_;
 
   // Iterator support.
   virtual int InputCount() V8_FINAL V8_OVERRIDE { return inputs_.length(); }
   virtual LOperand* InputAt(int i) V8_FINAL V8_OVERRIDE { return inputs_[i]; }
 
   virtual int TempCount() V8_FINAL V8_OVERRIDE { return 0; }
   virtual LOperand* TempAt(int i) V8_FINAL V8_OVERRIDE { return NULL; }
 };
 
@@ skipping 964 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(LChunkBuilder);
 };
 
 #undef DECLARE_HYDROGEN_ACCESSOR
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_IA32_LITHIUM_IA32_H_