Don't break ascent in the overscaled tile phase

[kkaefer]

We optimize our updateRenderable algorithm by breaking ascent when we've already checked a certain tile. So far, we've compared the UnwrappedTileIDs, but they don't include the overscale component. When ascending through overscaled tile IDs, we've stopped the ascent too early, when we should've kept the search going. This resulted in tiles not getting rendered even though they were available.

[ChrisLoer]

As always with update_renderables logic it took me a while to feel like I understood what's going on, but this looks good to me. Also looks like GL JS was already using overscaled tile IDs in its equivalent logic:

https://github.com/mapbox/mapbox-gl-js/blob/a1233cb33e3b55cde90b52b908cb4d8f4b6864e6/src/source/source_cache.js#L373-L386

[kkaefer]

Thanks for checking that JS works correctly!