THE FONDAS: A Hollywood Dynasty by Peter Collier (G. P. Putnam's Sons: $22.95; 300 pp.) . Peter Collier and David Horowitz are best known for their skeptical portraits of influential American families--the Rockefellers, the Kennedys, the Fords--and this book carries that tradition to Hollywood. Readers are likely to be disappointed with this volume, however, for Collier, working alone, inadvertently demonstrates that the investigative-reporting approach used in the earlier books doesn't translate to the entertainment field. It may not be Collier's fault, given Hollywood's love of publicity, that there's little new information about the Fondas to uncover, but he compounds the problem by failing to provide new or deeper analysis.