Description of Change

The current Grid measurement algorithm measures cells in Auto rows/columns more than is strictly necessary; a side-effect of the extra measure at the final Auto row/column size on Windows is that the underlying platform is confused about control size changes and does not report them correctly to the containing controls (thus, the non-update issue reported in #12103).

One of the reasons for the extra measurements stems from updating the sizes of Star rows/columns after all of the Auto values have been determined. The algorithm assumes the need for this any time a cell intersects an Auto row or column in any direction. However, in many cases either the row or column is entirely pre-computable, because the Grid is constrained in that direction and there are no Auto values. In those situations, we can compute the value for Star in that direction up front, and avoid multiple measurements. Pre-computing also means that we have final values for width/height to use with controls where the measurements are interdependent (e.g., with Images where the aspect ratio affects the measurement results, like in #7388).

Pre-computing also means that we can avoid the duplicate measure scenarios originally addressed by #12660, so we no longer need to cache the first measurement values.

These changes pre-compute all cell sizes where possible and avoid secondary measures of Auto values. They also add a benchmark for the GridLayoutManager so we can verify that future fixes don't adversely impact performance.

The benchmark is limited to the performance of the GridLayoutManager specifically; it does not speak to the performance of the Grid on any actual platform.

Benchmarks before these changes:

After these changes:

Issues Fixed

Fixes #12103
Fixes #7388
Fixes #7363
Fixes #11453
Fixes #10799
Fixes #9078
Fixes #5363