I realize this isn't what you are looking for, but PithHelmet does this in Safari.
You could also try Privoxy I've never used it myself, but it is free, and it is a system-level thingy, so it will work with any web browser. I've heard that it also intercepts other things, too, like Software Update \
Yeah, Safari + PithHelmet is really the way to go. Popup blocking, Ad blocking and content collapsing, speed, accuracy, beauty. No other browser can stand up to that IMO.
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You could also try Privoxy I've never used it myself, but it is free, and it is a system-level thingy, so it will work with any web browser. I've heard that it also intercepts other things, too, like Software Update \