[parser] Make reusable_preparser really reusable

BUG=
R=marja@chromium.org

Review-Url: https://codereview.chromium.org/2738153003
Cr-Commit-Position: refs/heads/master@{#43716}

src/parsing/parser.cc

@@ -2783,26 +2783,11 @@ Parser::LazyParsingResult Parser::SkipFunction(
   // AST. This gathers the data needed to build a lazy function.
   TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"), "V8.PreParse");
 
-  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
-  }
   // Aborting inner function preparsing would leave scopes in an inconsistent
   // state; we don't parse inner functions in the abortable mode anyway.
   DCHECK(!is_inner_function || !may_abort);
 
-  PreParser::PreParseResult result = reusable_preparser_->PreParseFunction(
+  PreParser::PreParseResult result = reusable_preparser()->PreParseFunction(
       kind, function_scope, parsing_module_, is_inner_function, may_abort,
       use_counts_);
 
@@ -2818,7 +2803,7 @@ Parser::LazyParsingResult Parser::SkipFunction(
     *ok = false;
     return kLazyParsingComplete;
   }
-  PreParserLogger* logger = reusable_preparser_->logger();
+  PreParserLogger* logger = reusable_preparser()->logger();
   function_scope->set_end_position(logger->end());
   Expect(Token::RBRACE, CHECK_OK_VALUE(kLazyParsingComplete));
   total_preparse_skipped_ +=

src/parsing/parser.h

@@ -299,6 +299,26 @@ class V8_EXPORT_PRIVATE Parser : public NON_EXPORTED_BASE(ParserBase<Parser>) {
     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);