In flutter/engine#50146 OpenGLES goldens were introduced, but the OpenGLES renderer holds textures with the Y flipped. In order to account for this we flip the textures upside down on the CPU before writing the png files. In theory that flipping should be able to be performed by the blit pass for better performance.

In Vulkans case the destination rect for the blit can have negative y coordinates, which should flip the texture.