Improve StringIndexOf.

src/string.js

 // Copyright 2006-2009 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 85 matching lines @@
   return %StringBuilderConcat(parts, len + 1, "");
 }
 
 // Match ES3 and Safari
 %FunctionSetLength(StringConcat, 1);
 
 
 // ECMA-262 section 15.5.4.7
 function StringIndexOf(pattern /* position */) {  // length == 1
   var subject = TO_STRING_INLINE(this);
-  var pattern = TO_STRING_INLINE(pattern);
-  var subject_len = subject.length;
-  var pattern_len = pattern.length;
   var index = 0;
   if (%_ArgumentsLength() > 1) {
-    var arg1 = %_Arguments(1);  // position
-    index = TO_INTEGER(arg1);
+    index = %_Arguments(1);  // position
+    index = TO_INTEGER(index);
+    if (index < 0) index = 0;
+    if (index > subject.length) index = subject.length;
   }
-  if (index < 0) index = 0;
-  if (index > subject_len) index = subject_len;
-  if (pattern_len + index > subject_len) return -1;
-  return %StringIndexOf(subject, pattern, index);
+  return %StringIndexOf(subject, TO_STRING_INLINE(pattern), index);
 }
 
 
 // ECMA-262 section 15.5.4.8
 function StringLastIndexOf(pat /* position */) {  // length == 1
   var sub = TO_STRING_INLINE(this);
   var subLength = sub.length;
   var pat = TO_STRING_INLINE(pat);
   var patLength = pat.length;
   var index = subLength - patLength;
@@ skipping 783 matching lines @@
     "italics", StringItalics,
     "small", StringSmall,
     "strike", StringStrike,
     "sub", StringSub,
     "sup", StringSup
   ));
 }
 
 
 SetupString();