Fix ARM build on mac.

src/arm/regexp-macro-assembler-arm.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 205 matching lines @@
   // Which mode to generate code for (ASCII or UC16).
   Mode mode_;
 
   // One greater than maximal register index actually used.
   int num_registers_;
 
   // Number of registers to output at the end (the saved registers
   // are always 0..num_saved_registers_-1)
   int num_saved_registers_;
 
-  // Manage a small pre-allocated pool for writing label targets
-  // to for pushing backtrack addresses.
-  int backtrack_constant_pool_offset_;
-  int backtrack_constant_pool_capacity_;
-
   // Labels used internally.
   Label entry_label_;
   Label start_label_;
   Label success_label_;
   Label backtrack_label_;
   Label exit_label_;
   Label check_preempt_label_;
   Label stack_overflow_label_;
 };
 
 #endif  // V8_INTERPRETED_REGEXP
 
 
 }}  // namespace v8::internal
 
 #endif  // V8_ARM_REGEXP_MACRO_ASSEMBLER_ARM_H_