Fix Globe material issues.

[bagnell]

• Fix shader compilation fail on pick.
• Fix globe materials when enableLighting = false.

Fixes #6042 and #6039.

[cesium-concierge]

@bagnell, thanks for the pull request! Maintainers, we have a signed CLA from @bagnell, so you can review this at any time.

⚠️ I noticed that CHANGES.md has not been updated. If this change updates the public API in any way, fixes a bug, or makes any non-trivial update, please add a bullet point to CHANGES.md and comment on this pull request so we know it was updated. For more info, see the Pull Request Guidelines.

---

I am a bot who helps you make Cesium awesome! Contributions to my configuration are welcome.

🌍 🌎 🌏

[pjcozzi]

Thanks @bagnell. Please open a separate PR if there is a reasonable way to add unit tests, e.g., render globe materials with lighting set to false.

[bagnell]

The existing tests already have enableLighting = false; because it's the default. They're also broken.

They're in SceneSpec.js (should be in GlobeSpec.js). The polls finish when the scene doesn't render [0, 0, 0, 0] but the background color is [0, 0, 0, 255] so it finishes immediately. Also, after the polls are finished, there are no tests. Change the tests to the below and they fail:

var globe = s.globe;
return pollToPromise(function() {
    globe._surface._debug.enableDebugOutput = true;
    s.render();
    return globe._surface.tileProvider.ready && globe._surface._tileLoadQueueHigh.length === 0 && globe._surface._tileLoadQueueMedium.length === 0 && globe._surface._tileLoadQueueLow.length === 0 && globe._surface._debug.tilesWaitingForChildren === 0;
}).then(function() {
    expect(s).notToRender([0, 0, 0, 255]);
});