Use in-object fields instead of private symbols for regexp slots.

src/js/regexp.js

 // 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.
 
 (function(global, utils) {
 
 %CheckIsBootstrapping();
 
 // -------------------------------------------------------------------
 // Imports
 
 var FLAG_harmony_tolength;
 var GlobalObject = global.Object;
 var GlobalRegExp = global.RegExp;
 var InternalPackedArray = utils.InternalPackedArray;
 var MakeTypeError;
-var regExpFlagsSymbol = utils.ImportNow("regexp_flags_symbol");
-var regExpSourceSymbol = utils.ImportNow("regexp_source_symbol");
 
 utils.ImportFromExperimental(function(from) {
   FLAG_harmony_tolength = from.FLAG_harmony_tolength;
 });
 
 utils.Import(function(from) {
   MakeTypeError = from.MakeTypeError;
 });
 
 // -------------------------------------------------------------------
@@ skipping 298 matching lines @@
     var matchEnd = RegExpLastMatchInfo[CAPTURE(index + 1)];
     if (matchStart == -1 || matchEnd == -1) return '';
     return %_SubString(LAST_SUBJECT(RegExpLastMatchInfo), matchStart, matchEnd);
   };
 }
 
 
 // ES6 21.2.5.4, 21.2.5.5, 21.2.5.7, 21.2.5.12, 21.2.5.15.
 function GetRegExpFlagGetter(name, mask) {
   var getter = function() {
-    if (!IS_SPEC_OBJECT(this)) {
+    if (!IS_REGEXP(this)) {
       throw MakeTypeError(kRegExpNonObject, name, TO_STRING(this));
     }
-    var flags = this[regExpFlagsSymbol];
-    if (IS_UNDEFINED(flags)) {
-      throw MakeTypeError(kRegExpNonRegExp, TO_STRING(this));
-    }
-    return !!(flags & mask);
+    return !!(%_RegExpFlags(this) & mask);
   };
   %FunctionSetName(getter, name);
   %SetNativeFlag(getter);
   return getter;
 }
 
 
 // ES6 21.2.5.10.
 function RegExpGetSource() {
-  if (!IS_SPEC_OBJECT(this)) {
+  if (!IS_REGEXP(this)) {
     throw MakeTypeError(kRegExpNonObject, "RegExp.prototype.source",
                         TO_STRING(this));
   }
-  var source = this[regExpSourceSymbol];
-  if (IS_UNDEFINED(source)) {
-    throw MakeTypeError(kRegExpNonRegExp, TO_STRING(this));
-  }
-  return source;
+  return %RegExpSource(this);
 }
 
 %SetNativeFlag(RegExpGetSource);
 
 // -------------------------------------------------------------------
 
 %FunctionSetInstanceClassName(GlobalRegExp, 'RegExp');
 %FunctionSetPrototype(GlobalRegExp, new GlobalObject());
 %AddNamedProperty(
     GlobalRegExp.prototype, 'constructor', GlobalRegExp, DONT_ENUM);
@@ skipping 92 matching lines @@
 
 utils.Export(function(to) {
   to.GetRegExpFlagGetter = GetRegExpFlagGetter;
   to.RegExpExec = DoRegExpExec;
   to.RegExpExecNoTests = RegExpExecNoTests;
   to.RegExpLastMatchInfo = RegExpLastMatchInfo;
   to.RegExpTest = RegExpTest;
 });
 
 })