Our real-estate market’s surprising refusal to cool down can be chalked up to a single, low-profile foreign player. The name Istithmar is still not exactly a mainstay of Manhattan conversation, but the Dubai-based firm’s purchases in the city make Trump look like an amateur apartment-flipper. In the past year alone, Istithmar, owned by the country’s royal family, set two major records in the field. It was the first to pay over $1,000 a foot for office space (on Park Avenue) as well as the first to pick up a hotel at over a million per room (W Union Square). The ease with which the firm parts with its funds has made some aristocratic jaws drop; best of all, though, Istithmar — whose moves account for 12 percent of all office and hotel purchases in the city last year — shows no signs of being done. They already found time to (unsuccessfully) bid on 5 Times Square, goosing up its price in the process.