This seems a bit unnecessary, there are elegant solutions already being built into mobile browsers which is by far the best place to address issues like this.
Opera on my phone automatically zooms whenever you tap a link near another link so you can select with no ambiguity, and I believe Chrome on Android does too:
Safari is notably lagging behind but it's a crappy browser... back button right next to the close tab button suffering from the exact problem you're describing.
I kind of assumed mobile browsers might already be doing this -- 'smudging' clicks a few pixels towards the nearest clickable region, whenever they land someplace neutral.
Still, if/when they don't, this seems helpful. In particular, if the HN up/down triangles had this, biased in the direction opposite each other, there'd be fewer mistaken votes on touch screens.