anchor.diff:  
     bool get inPlainSync => asyncState == AsyncModifier.Sync;
   
  +  /// Parse a compilation unit.
  +  ///
  +  /// This method is only invoked from outside the parser. As a result, this
  +  /// method takes the next token to be consumed rather than the last consumed
  +  /// token and returns the token after the last consumed token rather than the
  +  /// last consumed token.
  +  ///
     /// ```
     /// libraryDefinition:
     ///   scriptTag?
  
positive.code:   ///   methodDeclaration
    /// ;
    /// ```
    Token parseMember(Token token) {
      // TODO(brianwilkerson) Accept the last consumed token.
      token = parseMetadataStar(token);
      Token start = token;
      listener.beginMember(token);
      // TODO(danrubel): isFactoryDeclaration scans forward over modifiers
  
negative.code:     return token;
    }
  
    /// Parse a top-level declaration.
    ///
    /// This method is only invoked from outside the parser. As a result, this
    /// method takes the next token to be consumed rather than the last consumed
    /// token and returns the token after the last consumed token rather than the
    /// last consumed token.
    Token parseTopLevelDeclaration(Token token) {
      token =
          parseTopLevelDeclarationImpl(syntheticPreviousToken(token), null).next;
  