Clamp non-looped animations to start and stop times.

[emackey]

Fixes #7387.

If Cesium's current time went outside of a non-looping glTF animation time interval, Cesium would not perform one final update to push the animation as far as it could go in the direction of that time.

Here's a Sandcastle demo on master that tries to demonstrate the problem. The green area on the timeline shows where the animation is playing. If you jump the time into one of the outside areas (yellow or red), the cube won't update, it will remain frozen in some in-between state.

Here's the same Sandcastle demo on this branch.

[cesium-concierge]

Thanks for the pull request @emackey!

• ✔️ Signed CLA found.
• ❔ CHANGES.md was not updated.
  • If this change updates the public API in any way, please add a bullet point to CHANGES.md.
• ❔ 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.

[emackey]

I can't see what Travis is doing, but there's probably a failed test on here, I'll have to look into it.

[mramato]

I can't see what Travis is doing

Why not? You should be able to get the full log. Here you go either way.

  Scene/Model
    ✗ raises animation start, update, and stop events when removeOnStop is true
	Expected 5 to equal 4.
	<Jasmine>
	@Specs/Scene/ModelSpec.js:1776:41
	fulfilled/p<@Source/ThirdParty/when.js:194:34
	_then/<@Source/ThirdParty/when.js:295:13
	processQueue@Source/ThirdParty/when.js:645:11
	_resolve@Source/ThirdParty/when.js:331:16
	promiseResolve@Source/ThirdParty/when.js:357:11
	poller@Specs/pollToPromise.js:26:16
    ✗ Animates with an explicit stopTime
	Expected 3 to equal 2.
	<Jasmine>
	@Specs/Scene/ModelSpec.js:1846:39
	customizeJasmine/window.it/<@Specs/customizeJasmine.js:40:22
	<Jasmine>

[emackey]

OK, tests uncovered another edge case, where user's stop time happens before the animation's own stop time. This is fixed now, and new tests explicitly cover the edge cases I know about. Coverage remains at 100% for this section of code.

[emackey]

This is ready.

[mramato]

Looks simple and straightforward to me and can confirm the fix works as intended. @lilleyse did you want to take a look at this?

[lilleyse]

Looks good to me