Do not coerce lastIndex of a global RegExp in @@match and @@replace.

src/js/string.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
@@ skipping 133 matching lines @@
   return %StringLocaleCompare(TO_STRING(this), TO_STRING(other));
 }
 
 
 // ECMA-262 section 15.5.4.10
 function StringMatchJS(regexp) {
   CHECK_OBJECT_COERCIBLE(this, "String.prototype.match");
 
   var subject = TO_STRING(this);
   if (IS_REGEXP(regexp)) {
-    // Emulate RegExp.prototype.exec's side effect in step 5, even though
-    // value is discarded.
-    var lastIndex = TO_INTEGER(regexp.lastIndex);
     if (!regexp.global) return RegExpExecNoTests(regexp, subject, 0);
     var result = %StringMatch(subject, regexp, RegExpLastMatchInfo);
     if (result !== null) $regexpLastMatchInfoOverride = null;
     regexp.lastIndex = 0;
     return result;
   }
   // Non-regexp argument.
   regexp = new GlobalRegExp(regexp);
   return RegExpExecNoTests(regexp, subject, 0);
 }
@@ skipping 48 matching lines @@
   // ........ need to circument last match info override
   // .... function replace
   // ...... global search
   // ...... non-global search
   // .. string search
   // .... special case that replaces with one single character
   // ...... function replace
   // ...... string replace (with $-expansion)
 
   if (IS_REGEXP(search)) {
-    // Emulate RegExp.prototype.exec's side effect in step 5, even if
-    // value is discarded.
-    var lastIndex = TO_INTEGER(search.lastIndex);
-
     if (!IS_CALLABLE(replace)) {
       replace = TO_STRING(replace);
 
       if (!search.global) {
         // Non-global regexp search, string replace.
         var match = RegExpExec(search, subject, 0);
         if (match == null) {
           search.lastIndex = 0
           return subject;
         }
@@ skipping 958 matching lines @@
   to.StringLastIndexOf = StringLastIndexOfJS;
   to.StringMatch = StringMatchJS;
   to.StringReplace = StringReplace;
   to.StringSlice = StringSlice;
   to.StringSplit = StringSplitJS;
   to.StringSubstr = StringSubstr;
   to.StringSubstring = StringSubstring;
 });
 
 })