[sailfish-browser] Drop glScissor resetting workaround.
[sailfish-browser] Drop glScissor resetting workaround.

Now that we have one compositor per window we no longer need to manually
reset scissor box state.

sailfishos/sailfish-browser,sailfishos/sailfish-browser,sailfishos/sailfish-browser,sailfishos/sailfish-browser,sailfishos/sailfish-browser