Bless director Michael Curtiz and screenwriters Norman Krasna, Norman Panama, and Melvin Frank for starting off “White Christmas” on a good foot. Within a matter of seconds after the opening credits of the 1954 film have rolled on by, Bing Crosby begins crooning Irving Berlin’s supernal title song. A friend with whom I was watching the film couldn’t believe the audacity of this tack, seeing it as similar to delivering the punchline of a joke before the setup.