[Interpreter]: Add kRegList operand type for register list operands.

src/interpreter/bytecode-decoder.h

 // Copyright 2015 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_INTERPRETER_BYTECODE_DECODER_H_
 #define V8_INTERPRETER_BYTECODE_DECODER_H_
 
 #include <iosfwd>
 
 #include "src/interpreter/bytecode-register.h"
 #include "src/interpreter/bytecodes.h"
 
 namespace v8 {
 namespace internal {
 namespace interpreter {
 
 class BytecodeDecoder final {
  public:
   // Decodes a register operand in a byte array.
   static Register DecodeRegisterOperand(const uint8_t* operand_start,
                                         OperandType operand_type,
                                         OperandScale operand_scale);
 
+  // Decodes a register list operand in a byte array.
+  static RegisterList DecodeRegisterListOperand(const uint8_t* operand_start,
+                                                uint32_t count,
+                                                OperandType operand_type,
+                                                OperandScale operand_scale);
+
   // Decodes a signed operand in a byte array.
   static int32_t DecodeSignedOperand(const uint8_t* operand_start,
                                      OperandType operand_type,
                                      OperandScale operand_scale);
 
   // Decodes an unsigned operand in a byte array.
   static uint32_t DecodeUnsignedOperand(const uint8_t* operand_start,
                                         OperandType operand_type,
                                         OperandScale operand_scale);
 
   // Decode a single bytecode and operands to |os|.
   static std::ostream& Decode(std::ostream& os, const uint8_t* bytecode_start,
                               int number_of_parameters);
 };
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_INTERPRETER_BYTECODE_DECODER_H_