[js-perf-test] add microbenchmarks for String Iterators

test/js-perf-test/StringIterators/run.js

 // Copyright 2016 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.
 
 
 load('../base.js');
-load('generators.js');
+load('string-iterator.js');
+
 
 var success = true;
 
 function PrintResult(name, result) {
-  print(name + '-Generators(Score): ' + result);
+  print(name + '-StringIterators(Score): ' + result);
 }
 
 
 function PrintError(name, error) {
   PrintResult(name, error);
   success = false;
 }
 
 
 BenchmarkSuite.config.doWarmup = undefined;
 BenchmarkSuite.config.doDeterministic = undefined;
 
 BenchmarkSuite.RunSuites({ NotifyResult: PrintResult,
                            NotifyError: PrintError });