Blue-eyed, dark-haired Fairuza Balk weathered the storms of Oz, gradually breaking free from her fresh-faced little kid persona to plunge into dark and depressing film scenarios that ultimately reveal an optimism at her core. She worked first on TV in NBC's "The Best Christmas Pageant Ever" (1983) before beating out 1,200 girls to fill Dorothy's ruby slippers in Walter Murch's feature debut, "Return to Oz" (1985). Refusing to be traumatized by critics comparing her unfavorably to Judy Garland, Balk rebounded for more kid stuff as the well-meaning klutz Mildred Hubble in "The Worst Witch", a