The Goo Goo Dolls had a monster hit in 1998 with the ballad “Iris.” A megahit like that can catapult a band into a new level of stardom, but it can also loom over whatever the band tries to do for the rest of its career.For the Goo Goo Dolls, and particularly singer John Rzeznik, who wrote “Iris,” the song can be both a “blessing and a curse,” says bassist Robby Takac.“You have a big song. That’s a blessing. The curse is, people are expecting you to do that again,” Takac said in a recent phone interview. “We’ve had 14 songs in the top 10, but none of them was as big as ‘Iris.’ And most people