[parser] Make reusable_preparser really reusable

src/parsing/parser.h

 // Copyright 2012 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_PARSING_PARSER_H_
 #define V8_PARSING_PARSER_H_
 
 #include "src/ast/ast.h"
 #include "src/ast/scopes.h"
 #include "src/base/compiler-specific.h"
@@ skipping 281 matching lines @@
   ScriptCompiler::CompileOptions compile_options() const {
     return compile_options_;
   }
   bool consume_cached_parse_data() const {
     return compile_options_ == ScriptCompiler::kConsumeParserCache;
   }
   bool produce_cached_parse_data() const {
     return compile_options_ == ScriptCompiler::kProduceParserCache;
   }
 
+  PreParser* reusable_preparser() {
+    if (reusable_preparser_ == NULL) {
+      reusable_preparser_ =
+          new PreParser(zone(), &scanner_, stack_limit_, ast_value_factory(),
+                        &pending_error_handler_, runtime_call_stats_,
+                        parsing_on_main_thread_);
+#define SET_ALLOW(name) reusable_preparser_->set_allow_##name(allow_##name());
+      SET_ALLOW(natives);
+      SET_ALLOW(harmony_do_expressions);
+      SET_ALLOW(harmony_function_sent);
+      SET_ALLOW(harmony_trailing_commas);
+      SET_ALLOW(harmony_class_fields);
+      SET_ALLOW(harmony_object_rest_spread);
+      SET_ALLOW(harmony_dynamic_import);
+      SET_ALLOW(harmony_async_iteration);
+#undef SET_ALLOW
+    }
+    return reusable_preparser_;
+  }
+
   void ParseModuleItemList(ZoneList<Statement*>* body, bool* ok);
   Statement* ParseModuleItem(bool* ok);
   const AstRawString* ParseModuleSpecifier(bool* ok);
   void ParseImportDeclaration(bool* ok);
   Statement* ParseExportDeclaration(bool* ok);
   Statement* ParseExportDefault(bool* ok);
   void ParseExportClause(ZoneList<const AstRawString*>* export_names,
                          ZoneList<Scanner::Location>* export_locations,
                          ZoneList<const AstRawString*>* local_names,
                          Scanner::Location* reserved_loc, bool* ok);
@@ skipping 899 matching lines @@
 
  private:
   ParserTarget** variable_;
   ParserTarget* previous_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_PARSER_H_