[regexp] Avoid unneeded accesses to lastIndex

test/mjsunit/regexp.js

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 546 matching lines @@
         return string;
       },
       length: 0
     };
 
 var re = /str/;
 log = [];
 re.lastIndex = fakeLastIndex;
 var result = re.exec(fakeString);
 assertEquals(["str"], result);
-assertEquals(["ts", "li"], log);
+assertEquals(["ts"], log);
 
 // Again, to check if caching interferes.
 log = [];
 re.lastIndex = fakeLastIndex;
 result = re.exec(fakeString);
 assertEquals(["str"], result);
-assertEquals(["ts", "li"], log);
+assertEquals(["ts"], log);
 
 // And one more time, just to be certain.
 log = [];
 re.lastIndex = fakeLastIndex;
 result = re.exec(fakeString);
 assertEquals(["str"], result);
-assertEquals(["ts", "li"], log);
+assertEquals(["ts"], log);
 
 // Now with a global regexp, where lastIndex is actually used.
 re = /str/g;
 log = [];
 re.lastIndex = fakeLastIndex;
 var result = re.exec(fakeString);
 assertEquals(["str"], result);
 assertEquals(["ts", "li"], log);
 
 // Again, to check if caching interferes.
@@ skipping 127 matching lines @@
 assertThrows("RegExp.prototype.toString.call('')", TypeError);
 assertThrows("RegExp.prototype.toString.call(false)", TypeError);
 assertThrows("RegExp.prototype.toString.call(true)", TypeError);
 
 // Test mutually recursive capture and backreferences.
 assertEquals(["b", "", ""], /(\2)b(\1)/.exec("aba"));
 assertEquals(["a", "", ""], /(\2).(\1)/.exec("aba"));
 assertEquals(["aba", "a", "a"], /(.\2).(\1)/.exec("aba"));
 assertEquals(["acbc", "c", "c"], /a(.\2)b(\1)$/.exec("acbc"));
 assertEquals(["acbc", "c", "c"], /a(.\2)b(\1)/.exec("aabcacbc"));