Shares in cleaning robot maker iRobot (NASDAQ:IRBT) fell by nearly half after the European Commission said it intends to block its acquisition by Amazon (NASDAQ:AMZN).The refusal raised the specter of bankruptcy for iRobot. That fear also engulfed Spirit Airlines (NASDAQ:SAVE) after its merger with JetBlue (NASDAQ:JBLU) was rejected in the U.S.IRBT stock, which had been trading at $27.60 early on Jan. 18, opened this morning at about $16.94. That’s a market capitalization of just $465 million.Amazon was rep ...