Apple has begun airing a fourth iPhone ad, focused on the handset’s version of Safari. “This is not a watered-down version of the internet,” the ad voiceover claims. “Or the ‘mobile’ version of the internet. Or the kinda-sorta-looks-like-the-internet internet. It’s just the internet. On Your Phone.” The new commercial, like the other three iPhone ads that began airing earlier this week, ends with a “Coming…