[interpreter] Remove BytecodeArrayBuilder::Illegal().

src/interpreter/bytecode-array-writer.cc

 // 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.
 
 #include "src/interpreter/bytecode-array-writer.h"
 
 #include <iomanip>
 #include "src/interpreter/source-position-table.h"
 
 namespace v8 {
@@ skipping 23 matching lines @@
   int bytecode_offset = static_cast<int>(bytecodes()->size());
   const BytecodeSourceInfo& source_info = node->source_info();
   if (source_info.is_valid()) {
     source_position_table_builder_->AddPosition(bytecode_offset,
                                                 source_info.source_position(),
                                                 source_info.is_statement());
   }
 }
 
 void BytecodeArrayWriter::EmitBytecode(const BytecodeNode* const node) {
+  DCHECK_NE(node->bytecode(), Bytecode::kIllegal);
+
   OperandScale operand_scale = node->operand_scale();
   if (operand_scale != OperandScale::kSingle) {
     Bytecode prefix = Bytecodes::OperandScaleToPrefixBytecode(operand_scale);
     bytecodes()->push_back(Bytecodes::ToByte(prefix));
   }
 
   Bytecode bytecode = node->bytecode();
   bytecodes()->push_back(Bytecodes::ToByte(bytecode));
 
   int register_operand_bitmap = Bytecodes::GetRegisterOperandBitmap(bytecode);
@@ skipping 40 matching lines @@
 // override
 void BytecodeArrayWriter::FlushBasicBlock() {}
 
 int BytecodeArrayWriter::GetMaximumFrameSizeUsed() {
   return max_register_count_ * kPointerSize;
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8