Create ast/ and parsing/ subdirectories and move appropriate files

src/parameter-initializer-rewriter.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_PARAMETER_EXPRESSION_REWRITER_H_
-#define V8_PARAMETER_EXPRESSION_REWRITER_H_
-
-#include "src/ast.h"
-
-namespace v8 {
-namespace internal {
-
-
-void RewriteParameterInitializerScope(uintptr_t stack_limit,
-                                      Expression* initializer, Scope* old_scope,
-                                      Scope* new_scope);
-
-
-}  // namespace internal
-}  // namespace v8
-
-#endif  // V8_PARAMETER_EXPRESSION_REWRITER_H_