I don't think that will work. According to Apple, power adapters for Intel-based Apple notebooks are available in 45W, 60W, and 85W varieties. Although you should always use the proper wattage adapter for your Apple notebook, you can use an adapter of a higher wattage without issue.
An iPhone charger delivers 5 Watts (5 volts at 1000 mA). A Retina iPad mini charger delivers 10 watts (5.1 volts at 2100 mA).
Not enough power to charge a MacBook Pro. Plus the new MacBooks have a much longer battery life than do the old ones. It is actually good for the battery to be allowed to fully discharge. It is not good practice to leave your MacBook Pro on AC power all the time. If you work where there is always AC power available, once a week, unplug the computer and let it run on the battery until it goes to sleep. If you are worried about losing work, just unplug the computer overnight.
It is not good to fully discharge the lipo battery in your laptop. Unlike the older ni-cd or ni-mh batteries, li-po cells should never be discharged completely or charged to above 80%iirc. While the battery is in these states the cell is stressed. The damage doesn't occur from leaving the battery on a charger for a long amount of time but from being kept at a capacity above or below it's ideal rating. You could trickle charge it all you want, if it never goes above 80% you would be doing your battery a service.