Fix split with regexp for frog.

frog/world.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /** The one true [World]. */
 World world;
 
 /**
  * Experimental phase to enable await, only set when using the
  * await/awaitc.dart entrypoint.
@@ skipping 312 matching lines @@
       // TODO(jmesserly): this doesn't work if I write "new Set<String>.from"
       // List of JS reserved words.
       _jsKeywords = new Set.from([
         'break', 'case', 'catch', 'continue', 'debugger', 'default',
         'delete', 'do', 'else', 'finally', 'for', 'function', 'if',
         'in', 'instanceof', 'new', 'return', 'switch', 'this', 'throw',
         'try', 'typeof', 'var', 'void', 'while', 'with',
         'class', 'enum', 'export', 'extends', 'import', 'super',
         'implements', 'interface', 'let', 'package', 'private',
         'protected', 'public', 'static', 'yield',
+        // Hack: we don't want Dart's String.split to overwrite the existing
+        // JS String.split method. By adding 'split' to the keyword-set we
+        // ensure that frog will not use the 'split' name but mangle it, thus
+        // leaving the original JS String.split untouched.
+        'split',
         'native']);
     }
     if (_jsKeywords.contains(name)) {
       return name + '_';
     } else {
       // regexs for better perf?
       return name.replaceAll(@'$', @'$$').replaceAll(':', @'$');
     }
   }
 
@@ skipping 276 matching lines @@
 
   withTiming(String name, f()) {
     final sw = new Stopwatch();
     sw.start();
     var result = f();
     sw.stop();
     info('$name in ${sw.elapsedInMs()}msec');
     return result;
   }
 }