Bert Lahr, who died in 1967, is best remembered for having played the Cowardly Lion in the 1939 film version of "The Wizard of Oz." That's not a bad way to crash posterity, but in his day Mr. Lahr was better known as Broadway's most beloved low comedian, a scene-stealing burlesque clown who cavorted to convulsively funny effect through such musicals as Cole Porter's "DuBarry Was a Lady" and Harold Arlen's "Life Begins at 8:40." So it was quite a surprise when the producer of the first Broadway production of Samuel Beckett's "Waiting for Godot," soon to be hailed as one of the greatest...