anchor.diff:      // issues with problematic elements like '__proto__'. Another
       // option would be to throw an exception if the hash code isn't a
       // number.
  -    return JS('int', '# & 0x3ffffff', element.hashCode);
  +    return JS('int', '# & #', element.hashCode, _mask30);
     }
   
     static bool _hasTableEntry(var table, var key) {
  
positive.code:     // way, we avoid converting them to strings when we use them as
      // keys in the JavaScript hash table object.
      return element is num &&
          JS('bool', '(# & 0x3ffffff) === #', element, element);
    }
  
    int _computeHashCode(var element) {
  
negative.code:     // issues with problematic elements like '__proto__'. Another
      // option would be to throw an exception if the hash code isn't a
      // number.
      return JS('int', '# & #', element.hashCode, _mask30);
    }
  
    static _getTableEntry(var table, var key) {
  