Slow performance of auto dimensions

We found out that defining at least one of the dimensions to be 100%, instead of keeping them both auto, improves performance a lot. We were able to achieve 3x frame time improvement (12ms -> 4ms) by going through every style we have and setting width to 100% when it does not break the UI (it mostly never does for auto-auto cases).

It would be nice though if the algorithm would be able to detect these scenarios better (of when 100% width gives the same result as auto) and avoid the expensive auto dimension resolve recursion / whatever in the process costs so much.

For now we changed the default values for style's dimensions to be 100% width and 100% height, so the user explicitly sets it to auto, with the goal being preserving as much performance as possible.

Speaking without knowledge, perhaps the algorithm could try to select a dimension according to current flex direction, usually width, and see that if there is only one relative child with flexGrow > 0, it could treat its {auto, auto} dimensions as {100%, auto} instead, for less algorithmic complexity but hopefully guaranteed same result?

The issue names no files, tests, or entry points. Start by tracing the auto-dimension resolution recursion and comparing auto/auto with 100% width under the described flexGrow and flex-direction conditions. Done means preserving layout results while demonstrating that equivalent cases avoid the reported performance cost.