Revert of [builtins] Also migrate String.prototype.toLowerCase/toUpperCase to C++.

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 469 matching lines @@
     }
   }
 
   var end = start + len;
   if (end > s.length) end = s.length;
 
   return %_SubString(s, start, end);
 }
 
 
+// ECMA-262, 15.5.4.16
+function StringToLowerCaseJS() {
+  CHECK_OBJECT_COERCIBLE(this, "String.prototype.toLowerCase");
+
+  return %StringToLowerCase(TO_STRING(this));
+}
+
+
+// ECMA-262, 15.5.4.17
+function StringToLocaleLowerCase() {
+  CHECK_OBJECT_COERCIBLE(this, "String.prototype.toLocaleLowerCase");
+
+  return %StringToLowerCase(TO_STRING(this));
+}
+
+
+// ECMA-262, 15.5.4.18
+function StringToUpperCaseJS() {
+  CHECK_OBJECT_COERCIBLE(this, "String.prototype.toUpperCase");
+
+  return %StringToUpperCase(TO_STRING(this));
+}
+
+
+// ECMA-262, 15.5.4.19
+function StringToLocaleUpperCase() {
+  CHECK_OBJECT_COERCIBLE(this, "String.prototype.toLocaleUpperCase");
+
+  return %StringToUpperCase(TO_STRING(this));
+}
+
+
 // ES6 draft, revision 26 (2014-07-18), section B.2.3.2.1
 function HtmlEscape(str) {
   return %_Call(StringReplace, TO_STRING(str), /"/g, """);
 }
 
 
 // ES6 draft, revision 26 (2014-07-18), section B.2.3.2
 function StringAnchor(name) {
   CHECK_OBJECT_COERCIBLE(this, "String.prototype.anchor");
   return "<a name=\"" + HtmlEscape(name) + "\">" + TO_STRING(this) +
@@ skipping 288 matching lines @@
   "match", StringMatchJS,
   "normalize", StringNormalize,
   "repeat", StringRepeat,
   "replace", StringReplace,
   "search", StringSearch,
   "slice", StringSlice,
   "split", StringSplitJS,
   "substring", StringSubstring,
   "substr", StringSubstr,
   "startsWith", StringStartsWith,
+  "toLowerCase", StringToLowerCaseJS,
+  "toLocaleLowerCase", StringToLocaleLowerCase,
+  "toUpperCase", StringToUpperCaseJS,
+  "toLocaleUpperCase", StringToLocaleUpperCase,
 
   "link", StringLink,
   "anchor", StringAnchor,
   "fontcolor", StringFontcolor,
   "fontsize", StringFontsize,
   "big", StringBig,
   "blink", StringBlink,
   "bold", StringBold,
   "fixed", StringFixed,
   "italics", StringItalics,
@@ skipping 12 matching lines @@
   to.StringLastIndexOf = StringLastIndexOf;
   to.StringMatch = StringMatchJS;
   to.StringReplace = StringReplace;
   to.StringSlice = StringSlice;
   to.StringSplit = StringSplitJS;
   to.StringSubstr = StringSubstr;
   to.StringSubstring = StringSubstring;
 });
 
 })