Comment 13 for bug 1946599

I instrumented further the code, and here are my observations so far:

When launching firefox, the very first call to `GLLibraryEGL::CreateDisplay()` returns a valid EGL display. This is being called from `RenderThread::CreateGLContextEGL()`, from the app's main process.

Subsequent calls to `GLLibraryEGL::CreateDisplay()` follow a different code path (from `GLContextProviderEGL::CreateHeadless()`, from child (content) processes), and those invariably return `null`, which results in WebGL not working.