I would also point out that it is impossible to raise the concentration of chloride alone -- you also raise the concentration of a conjugate cation. In the case of the two part example, your sodium goes up an equal amount in molar concentration. The result is that you see a rise in salinity over time, prompting a water change, much before you see a substantially increased chloride concentration.
The alternative would be to take out a portion of the saltwater and replace it with RO/DI to lower the salinity back, which over time would cause a decrease in calcium and alkalinity and an increase in sodium and chloride (you are essentially letting your corals take out the calcium and carbonate, and you are adding sodium chloride in its place). We know the effects of low calcium and low alkalinity, and yes that would inhibit calcification.
Also, as was already pointed out by Tom, chloride represents such an overwhelming portion of the anions in saltwater that there really isn't a ton of wiggle room to increase it, and even if you did it wouldn't be by a ton. Indeed, by definition you'd have to cut into your other anions to maintain a constant salinity and increase chloride, meaning you'd be cutting into things like bicarbonate/carbonate, borate (your buffering compounds), a bit of sulfate, a little fluoride and bromide, and I'm sure some other anions that represent a very small portion of total salts.
The point is, you can't increase chloride without decreasing or otherwise affecting other things, and we know that many of these resultant changes inhibit calcification (like lowering your calcium and alkalinity for example). So even in theory it is not possible to test the affect of increased chloride as it is not possible to increase it substantially without effecting other variables known to affect calcification.
