452e630ee2
The raw pointer isn't a reliable id as the allocator can reuse an address that's just been released for another layer. This will fix Fuchsia bug FL-216. This problem was not affecting non-Fuchsia Flutter probably because non-Fuchsia Flutter purges the raster cache key much more frequently so we won't see a key collision. In Fuchsia, as the key has to wait for the Vulkan surface to render asynchronously, this suddenly becomes an issue.