EGL_ANGLE_experimental_present_path was enabled for fast rendering to SwapChain by ANGLE. But current gecko does not request ANGLE to render to SwapChain for WebRender. Then we do not need to use EGL_ANGLE_experimental_present_path anymore. But Its usage still has a side effect that y is flipped. But OS compositor implementation on Windows does not want it. And it seems not good to continue to use EGL_ANGLE_experimental_present_path since it is experimental feature.
But when EGL_ANGLE_experimental_present_path is removed, rendering result of frame buffer is y flipped with ANGLE compared to other OpenGL implementation. It needs to be handled in WR. It is similar to chromium.
Differential Revision: https://phabricator.services.mozilla.com/D50604
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extra : moz-landing-system : lando
