anchor.diff:  
   /** A matcher for functions that throw FormatException */
   const Matcher throwsFormatException =
  -    const _Throws(isFormatException);
  -
  -class _FormatException extends _ExceptionMatcher {
  +    const Throws(isFormatException);
  +
  +class _FormatException extends ExceptionMatcher {
     const _FormatException() : super("FormatException");
     bool matches(item, MatchState matchState) => item is FormatException;
   }
  
positive.code: 
  /** A matcher for functions that throw NotNullPointerException */
  const Matcher throwsNullPointerException =
      const _Throws(isNullPointerException);
  
  class _NullPointerException extends _ExceptionMatcher {
    const _NullPointerException() : super("NullPointerException");
    bool matches(item, MatchState matchState) => item is NullPointerException;
  }
  
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;
  }
  