Fixes array reinitialization

[danicruz0415]

this.rects is an array, as set up in the constructor in line 10. I think this is a mistake. Instead of something like this: rects = [{object}, {object}, ...] this is creating something like this: {0: {object}, 1: {object}, ...}. I don't know if this can affect performance in any noticiable way but I think it may be worth changing.

BTW Thanks for the repo!