Game/Scene view window is flickering on resizing when Graphics APIs set to OpenGLCore, OpenGLES2 & OpenGLES3.

Steps to repro:
1. Create a new Project.
2. File > Build Settings > Player Settings.
3. Other Settings > Uncheck "Auto-Graphics API for Window" checkbox.
4. Add OpenGLCore > move to the top of the list > Restart.
5. Change the size of the Game/Scene view window.

Actual Result:
Game/Scene view window is flickering on resizing.

Expected Result:
Game/Scene view window should not be flickered on resizing.

Reproducible in:
2020.2.0a7, 2020.1.0b6, 2019.3.9f1, 2019.3.0f1.

Working Fine in:
2019.3.0b13.

Environment:
Only on Windows.