Flower power wilted long before the Gap opened its doors on the corner of Haight and Ashbury. But the store's low-key khakis can't camouflage the fact that this national chain is woefully out of place on the landmark corner once synonymous with counterculture. A neighborhood boycott has been in effect since the store opened its doors in 1986, but the irony escapes most tourist shoppers, who remain oblivious to the generation Gap between today's commercially exploited Haight Street and the long-lost Summer of Love.