WebGL context not available in VM

Since Qt 5.15.2 WebGL context is no longer detected when running the Qt application in a Ubuntu VM. However, WebGL is correctly found with previous Qt versions including 5.15.1.

On a native Ubuntu, it works correctly even with 5.15.2.

This issue can be reproduce by modifying the "WebEngine Widgets Minimal Example" Qt example so that it opens the attached "test_page.html" HTML page instead of the default one.