Bug 1031890 - Vertical homescreen takes a long time to load

Hmm, I'm just looking through this code again, and could you help me follow this? 

My question is why we do not call ```this.doRenderIcon``` when we get the img.onload callback? It seems like all the cached-icon-rendered handler does is wait to get that event for all icons, then sends back another event to the grid. Is it really needed?