anchor.diff:  
   /** A matcher for functions that throw ArgumentError */
   const Matcher throwsArgumentError =
  -    const _Throws(isArgumentError);
  -
  -class _ArgumentError extends _ExceptionMatcher {
  +    const Throws(isArgumentError);
  +
  +class _ArgumentError extends ExceptionMatcher {
     const _ArgumentError() : super("ArgumentError");
     bool matches(item, MatchState matchState) => item is ArgumentError;
   }
  
positive.code: 
  /** A matcher for functions that throw IndexOutOfRangeException */
  const Matcher throwsIndexOutOfRangeException =
      const _Throws(isIndexOutOfRangeException);
  
  class _IndexOutOfRangeException extends _ExceptionMatcher {
    const _IndexOutOfRangeException() : super("IndexOutOfRangeException");
    bool matches(item, MatchState matchState) => item is IndexOutOfRangeException;
  }
  
negative.code: 
  /** A matcher for functions that throw IllegalJSRegExpException */
  const Matcher throwsIllegalJSRegExpException =
      const Throws(isIllegalJSRegExpException);
  
  class _IllegalJSRegExpException extends ExceptionMatcher {
    const _IllegalJSRegExpException() : super("IllegalJSRegExpException");
    bool matches(item, MatchState matchState) => item is IllegalJSRegExpException;
  }
  