Create ast/ and parsing/ subdirectories and move appropriate files

src/ast/ast-expression-visitor.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_AST_EXPRESSION_VISITOR_H_
-#define V8_AST_EXPRESSION_VISITOR_H_
+#ifndef V8_AST_AST_EXPRESSION_VISITOR_H_
+#define V8_AST_AST_EXPRESSION_VISITOR_H_
 
 #include "src/allocation.h"
-#include "src/ast.h"
+#include "src/ast/ast.h"
+#include "src/ast/scopes.h"
 #include "src/effects.h"
-#include "src/scopes.h"
 #include "src/type-info.h"
 #include "src/types.h"
 #include "src/zone.h"
 
 namespace v8 {
 namespace internal {
 
 // A Visitor over a CompilationInfo's AST that invokes
 // VisitExpression on each expression node.
 
@@ skipping 18 matching lines @@
 #undef DECLARE_VISIT
 
   Expression* root_;
   int depth_;
 
   DISALLOW_COPY_AND_ASSIGN(AstExpressionVisitor);
 };
 }  // namespace internal
 }  // namespace v8
 
-#endif  // V8_AST_EXPRESSION_VISITOR_H_
+#endif  // V8_AST_AST_EXPRESSION_VISITOR_H_