The `DisplayListMatrixClipTracker` class performs the working of maintaining a stack of cull rects and transforms for classes in the engine that require such functionality (such as `DisplayListBuilder`, `DiffContext`, and `LayerStateStack`.
Until now it has been using a mixture of SkMatrix and SkM44 along with an SkRect to maintain this information, but that complexity involves overhead and implementation complexity which complicates future work on these areas.
By reimplementing the class to use Impeller geometry objects, the internal architecture is greatly simplified allowing for easier future maintenance.
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