ISTANBUL, May 16 : FIFA Secretary-General Mattias Grafstrom held a constructive and positive meeting with Iran's FA (FFIRI) President Mehdi Taj on Saturday, he told Reuters, expressing confidence about the country's participation at this year's World Cup. Iran are scheduled to play all three of their group matches in the United States but the team's participation in the June 11 to July 19 tournament has been in question since the U.S. and Israel attacked Iran in late February. "We've had an