anchor.diff:      return false;
     }
   
  -  Float32x4 firstWhere(bool test(Float32x4 element), {Float32x4 orElse()}) {
  +  Float32x4 firstWhere(bool test(Float32x4 element), {Float32x4 orElse()?}) {
       var len = this.length;
       for (var i = 0; i < len; ++i) {
         var element = this[i];
  
positive.code:     throw IterableElementError.noElement();
    }
  
    double singleWhere(bool test(double element), {double orElse()}) {
      var result = null;
      bool foundMatching = false;
      var len = this.length;
  
negative.code:     throw IterableElementError.noElement();
    }
  
    Int32x4 singleWhere(bool test(Int32x4 element), {Int32x4 orElse()?}) {
      var result = null;
      bool foundMatching = false;
      var len = this.length;
  