WIP: Implement ES6 Spread-calls

src/x64/codegen-x64.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_X64_CODEGEN_X64_H_
 #define V8_X64_CODEGEN_X64_H_
 
 #include "src/ast.h"
 #include "src/macro-assembler.h"
 
@@ skipping 81 matching lines @@
                                   parameter_count.immediate() : 0),
         receiver_mode_(receiver_mode),
         extra_displacement_to_last_argument_(
             extra_displacement_to_last_argument) { }
 
   Operand GetArgumentOperand(int index);
   Operand GetReceiverOperand() {
     DCHECK(receiver_mode_ == ARGUMENTS_CONTAIN_RECEIVER);
     return GetArgumentOperand(0);
   }
+  const Register& argument_count_reg() const { return argument_count_reg_; }
 
  private:
   const Register base_reg_;
   const Register argument_count_reg_;
   const int argument_count_immediate_;
   const StackArgumentsAccessorReceiverMode receiver_mode_;
   const int extra_displacement_to_last_argument_;
-
-  DISALLOW_IMPLICIT_CONSTRUCTORS(StackArgumentsAccessor);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_X64_CODEGEN_X64_H_