Sources on staff at “Dancing With the Stars” say the producers at the hit show have been very surprised by the outpouring of negative reaction to the casting of Chaz Bono as a contestant on the new season — launching Sept. 19 on WLS-Channel 7. “Of course, they knew there would be some anti-Bono calls and emails,” said a longtime “DWTS” insider. “But this has been more vicious and in larger volume than was anticipated. … Some of the comments are downright scary,” the source added. It seems some of the negativity may be coming from ABC viewers in the...