By Jeffrey Wasserstrom This posting about the politics of pop concerts in Shanghai is mostly about an American duo (Jan and Dean), whose hits included “Surf City,” and the hard-to-categorize Icelandic songstress Bjork, who last week made headlines and drew the ire of the Chinese state by saying the words “Tibet, Tibet” after performing a song called “Declare Independence" (on the heels of which, there was apparent tinkering with Harry Connick Jr.'s song list at......