Two quality companies are on sale -- but only one looks like a dip worth buying right now.When great businesses sell off, investors should lean in -- but only after checking whether the fundamentals are still doing the heavy lifting. Intuitive Surgical (ISRG 0.76%), the robotic-surgery leader behind the minimally invasive da Vinci system, and The Trade Desk (TTD 1.27%), a programmatic advertising platform for the open internet, have both been under pressure this year.Both companies reported fresh quarterly ...