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28d99854a6
This reverts commit a7a25d3b57f2066798ef8cd43600588e4697c9cd and relands our reland https://github.com/flutter/engine/pull/17915. Additionally, we fixed the cull rect logic in `OpacityLayer::Preroll` which is the root cause of https://github.com/flutter/flutter/issues/56298. We've always had that root problem before but it did not trigger performance issues because we were using the OpacityLayer's `paint_bounds`, instead of its child's `paint_bounds` for preparing the layer raster cache. A correct handling of the cull rect should allow us to cull at any level. It also turns out that our ios32 (iPhone4s) performacne can regress a lot without snapping. My theory is that although the picture has a fractional top left corner, many drawing operations inside the picture have integral coordinations. In older hardwares, keeping those coordinates integral seems to be performance critical. To avoid flutter/flutter#41654, the snapping will still be disabled if the matrix has non-scale-translation transformations.