Fix the viewport of ViewportQuad is not applied

[bbbbx]

fix #9167

[cesium-concierge]

Thanks for the pull request @bbbbx!

• ✔️ Signed CLA found.
• ❔ Unit tests were not updated.
  • Make sure you've updated tests to reflect your changes, added tests for any new code, and ran the code coverage tool.

Reviewers, don't forget to make sure that:

• Cesium Viewer works.
• Works in 2D/CV.
• Works (or fails gracefully) in IE11.

[ebogo1]

Thanks for the fix, @bbbbx!

@lilleyse - This change makes sense to me but I'm unable to reproduce the bugged behavior on my Linux machine. Any thoughts on this fix? I wonder if it's somehow possible to simulate a render state change in the ViewportQuad specs.

[lilleyse]

Should be straightforward to test by setting the rectangle after it's been created and observing that the command's render state has the correct viewport. Something like:

    it("updates rectangle", function () {
      var otherRectangle = new BoundingRectangle(0, 0, 4, 4);

      scene.primitives.add(viewportQuad);
      scene.renderForSpecs();

      viewportQuad.rectangle = otherRectangle;
      scene.renderForSpecs();
      expect(scene.frameState.commandList[0].renderState.viewport).toEqual(
        otherRectangle
      );
    });

[lilleyse]

Also I can confirm this PR fixes the bug.

[bbbbx]

Hi, I have added the test, could you review it again? Thanks @lilleyse @ebogo1

[ebogo1]

Thanks @bbbbx!