anchor.diff:    return UNINTERCEPTED(a[index]);
   }
   
  -void indexSet(var a, var index, var value) {
  +void indexSet$slow(var a, var index, var value) {
     if (isJsArray(a)) {
       if (index is !int) {
         throw new IllegalArgumentException(index);
  
positive.code: #source('native_helper.dart');
  #source('regexp_helper.dart');
  #source('string_helper.dart');
  
  /**
   * Returns true if both arguments are numbers.
  
negative.code:   return value !== null && JS('bool', @'#.constructor === Array', value);
  }
  
  add$slow(var a, var b) {
    if (checkNumbers(a, b)) {
      return JS('num', @'# + #', a, b);
    } else if (a is String) {
  