Polylines on 3D Tiles demo doesn't work in all browsers

I'm not sure if there is a supported check for this feature, or if it's just broken, but the Polylines on 3D Tiles demo doesn't work in Safari on the Mac I was using for testing

http://localhost:8080/Apps/Sandcastle/index.html?src=Polylines%20on%203D%20Tiles.html&label=All

If there is a supported check, we should be using it and notifying the user that the feature isn't supported on this browser. If there isn't a supported check, why is this Sandcastle broken on some browsers?

CC @lilleyse @likangning93

Start by reproducing the failure in Safari using the Polylines on 3D Tiles Sandcastle demo URL from the issue, then inspect that demo's browser-specific behavior and any existing support checks. Done means either the demo works across the affected browsers or clearly notifies users when the feature is unsupported.

Written by the indexing model from the issue text.