Templatize AstVisitor with its subclass

src/interpreter/bytecode-generator.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_GENERATOR_H_
 #define V8_INTERPRETER_BYTECODE_GENERATOR_H_
 
 #include "src/ast/ast.h"
 #include "src/interpreter/bytecode-array-builder.h"
 #include "src/interpreter/bytecode-label.h"
 #include "src/interpreter/bytecodes.h"
 
 namespace v8 {
 namespace internal {
 
 class CompilationInfo;
 
 namespace interpreter {
 
 class LoopBuilder;
 
-class BytecodeGenerator final : public AstVisitor {
+class BytecodeGenerator final : public AstVisitor<BytecodeGenerator> {
  public:
   explicit BytecodeGenerator(CompilationInfo* info);
 
   Handle<BytecodeArray> MakeBytecode();
 
-#define DECLARE_VISIT(type) void Visit##type(type* node) override;
+#define DECLARE_VISIT(type) void Visit##type(type* node);
   AST_NODE_LIST(DECLARE_VISIT)
 #undef DECLARE_VISIT
 
   // Visiting function for declarations list and statements are overridden.
-  void VisitDeclarations(ZoneList<Declaration*>* declarations) override;
-  void VisitStatements(ZoneList<Statement*>* statments) override;
+  void VisitDeclarations(ZoneList<Declaration*>* declarations);
+  void VisitStatements(ZoneList<Statement*>* statments);
 
  private:
   class ContextScope;
   class ControlScope;
   class ControlScopeForBreakable;
   class ControlScopeForIteration;
   class ControlScopeForTopLevel;
   class ControlScopeForTryCatch;
   class ControlScopeForTryFinally;
   class ExpressionResultScope;
@@ skipping 172 matching lines @@
   Register generator_state_;
   int try_catch_nesting_level_;
   int try_finally_nesting_level_;
 };
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_INTERPRETER_BYTECODE_GENERATOR_H_