Pass legacy const runtime flag to preparser appropriately

It was never being set to false in production (though it was in test-parsing.cc,
due to that test having its own flag-setting logic).

Review URL: https://codereview.chromium.org/1815033002

Cr-Commit-Position: refs/heads/master@{#34878}

src/parsing/parser.cc

@@ -4675,6 +4675,7 @@ PreParser::PreParseResult Parser::ParseLazyFunctionBodyWithPreParser(
     reusable_preparser_->set_allow_lazy(true);
 #define SET_ALLOW(name) reusable_preparser_->set_allow_##name(allow_##name());
     SET_ALLOW(natives);
+    SET_ALLOW(legacy_const);
     SET_ALLOW(harmony_sloppy);
     SET_ALLOW(harmony_sloppy_let);
     SET_ALLOW(harmony_do_expressions);

test/message/const-decl-no-init-sloppy.js

+// 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.
+//
+// Flags: --no-legacy-const --harmony-sloppy
+
+function f() {
+  const a;
+}

test/message/const-decl-no-init-sloppy.out

+# Copyright 2016 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.
+*%(basename)s:8: SyntaxError: Missing initializer in const declaration
+  const a;
+        ^
+SyntaxError: Missing initializer in const declaration

test/webkit/fast/js/arguments-expected.txt

@@ -157,7 +157,6 @@ PASS access_after_delete_extra_5(1, 2, 3, 4, 5) is 5
 PASS argumentsParam(true) is true
 PASS argumentsFunctionConstructorParam(true) is true
 PASS argumentsVarUndefined() is '[object Arguments]'
-FAIL argumentsConstUndefined() should be [object Arguments]. Threw exception SyntaxError: Missing initializer in const declaration
 PASS argumentCalleeInException() is argumentCalleeInException
 PASS shadowedArgumentsApply([true]) is true
 PASS shadowedArgumentsLength([]) is 0

test/webkit/fast/js/arguments.js

@@ -574,13 +574,6 @@ function argumentsVarUndefined()
 }
 shouldBe("argumentsVarUndefined()", "'[object Arguments]'");
 
-function argumentsConstUndefined()
-{
-    const arguments;
-    return String(arguments);
-}
-shouldBe("argumentsConstUndefined()", "'[object Arguments]'");
-
 function argumentCalleeInException() {
     try {
         throw "";