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