Install iterator meta objects via utils object.

src/js/string-iterator.js

Index: src/js/string-iterator.js
diff --git a/src/js/string-iterator.js b/src/js/string-iterator.js
index 660dc7c98b1ab56a65e1d19e0e4c18acd5c0096c..214f95d9baadb67dcf8a83bc65c4e453718c81cf 100644
--- a/src/js/string-iterator.js
+++ b/src/js/string-iterator.js
@@ -12,6 +12,7 @@
 // Imports
 
 var GlobalString = global.String;
+var IteratorPrototype = utils.ImportNow("IteratorPrototype");
 var iteratorSymbol = utils.ImportNow("iterator_symbol");
 var stringIteratorIteratedStringSymbol =
     utils.ImportNow("string_iterator_iterated_string_symbol");
@@ -80,7 +81,7 @@ function StringPrototypeIterator() {
 
 //-------------------------------------------------------------------
 
-%FunctionSetPrototype(StringIterator, {__proto__: $iteratorPrototype});
+%FunctionSetPrototype(StringIterator, {__proto__: IteratorPrototype});
 %FunctionSetInstanceClassName(StringIterator, 'String Iterator');
 
 utils.InstallFunctions(StringIterator.prototype, DONT_ENUM, [