Fix ARM build for gcc-4.6.

src/arm/assembler-arm.h

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // 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.
 //
@@ skipping 359 matching lines @@
 
 // -----------------------------------------------------------------------------
 // Machine instruction Operands
 
 // Class Operand represents a shifter operand in data processing instructions
 class Operand BASE_EMBEDDED {
  public:
   // immediate
   INLINE(explicit Operand(int32_t immediate,
          RelocInfo::Mode rmode = RelocInfo::NONE));
+  INLINE(static Operand Zero()) {
+    return Operand(static_cast<int32_t>(0));
+  }
   INLINE(explicit Operand(const ExternalReference& f));
   explicit Operand(Handle<Object> handle);
   INLINE(explicit Operand(Smi* value));
 
   // rm
   INLINE(explicit Operand(Register rm));
 
   // rm <shift_op> shift_imm
   explicit Operand(Register rm, ShiftOp shift_op, int shift_imm);
 
@@ skipping 1022 matching lines @@
  public:
   explicit EnsureSpace(Assembler* assembler) {
     assembler->CheckBuffer();
   }
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_ARM_ASSEMBLER_ARM_H_