Removed unused field, making clang happy again.

src/preparser.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 674 matching lines @@
 
    private:
     FunctionState** const function_state_stack_;
     FunctionState* const outer_function_state_;
     Scope** const scope_stack_;
     Scope* const outer_scope_;
     Scope scope_;
 
     int materialized_literal_count_;
     int expected_properties_;
-    LanguageMode language_mode_;
     bool is_generator_;
   };
 
   class BlockState {
    public:
     BlockState(Scope** scope_stack, ScopeType scope_type)
         : scope_stack_(scope_stack),
           outer_scope_(*scope_stack),
           scope_(*scope_stack, scope_type) {
       *scope_stack_ = &scope_;
@@ skipping 243 matching lines @@
                                "accessor_get_set");
     }
     *ok = false;
   }
 }
 
 
 } }  // v8::internal
 
 #endif  // V8_PREPARSER_H