It’s not as if Old Navy has to batten down its hatches. Old Navy has long been Gap Inc.’s largest-volume brand and cash cow, so it was a bit of a surprise when first-quarter results revealed less-than-satisfactory sales results at the brand, traced back to some fashion misses. “Overall results for Old Navy were primarily impacted by the women’s dress business, wherein, reviewing the season, we did not execute as effectively, and as a result, customers did not respond to our assortment the way we had intended,” Richard Dickson, Gap Inc.’s president and chief executive officer, said during a conference call with industry analysts and investors Thursday afternoon, following the release of the retailer’s first-quarter results. “Entering Q2, the seasonal women’s dress business continues to underperform our expectations, with weakness visible across the broader seasonal product assortment as well,” Dickson said. Swim and shorts were also under-performers.…