Leverage dirtry rect from cef's accelarated paint api

[csmoe]

https://docs.rs/cef-dll-sys/latest/aarch64-apple-darwin/cef_dll_sys/type.cef_accelerated_paint_info_common_t.html#structfield.capture_update_rect

This should save the gpu mem bandwith.

[TrueDoctor]

I'm not sure if this would have a significant impact, I guess we could reduce the number of pixels we have to copy but this is currently definitely not one of our bottlenecks