If anyone needed convincing that the stock market has become invincible, yesterday was the day.  Japan was shaken badly by another big earthquake, crude oil quotes were bounding above $110, Portugal was threatening to topple Europe’s financial house of cards, and the U.S. government was hours from shutting down. How did Wall Street take the news?  Like a pro, actually. The stage-managed panic was over almost before it began. Stocks dove on word from Japan — but not in a way that showed even the slightest sign of fear.  Rather, the market swooned in the fashion to which we’ve grown accustomed, violently shaking down widows, pensioners and a few other nervous nellies, but few “players.”  A precipitous, 100-point loss in the Dow was recouped in minutes, and when the dust had settled it were as though the day’s headlines were no more alarming than the kind of routine stuff that fills the “Daily Roundup” box on an inside page.  Now, I’m no Irving Fisher, and I don’t mean to suggest that stocks have reached a permanently high plateau.  Far more likely is that they will give back in a week everything gained since 2009.  In the meantime, however, it is clear that it will take far more to bring this market down than the latest evidence that the world is indeed going to hell in a handbasket.