Don't add polyline to update list twice

[hpinkos]

Fixes #7153

[cesium-concierge]

Thanks for the pull request @hpinkos!

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[mramato]

I'm pretty certain this exact code (or something like it) used to use indexOf and we changed it because it's a major performance killer. You are basically doing a linear search for every polyline being updated.

What is the root problem here, we are essentially updating the line twice and that leads to an error? Could we avoid the indexOf by using a dirty flag and simply not doing the second update if it's already been called?

[hpinkos]

Good call @mramato, I didn't realize polyline had a dirty flag.

[mramato]

I didn't realize polyline had a dirty flag.

I didn't either, glad it was that easy 😄 That being said, it would it make more sense to add this check in Polyline.js itself, that way it avoids calling _updatePolyline at all if it's already dirty?

[hpinkos]

@mramato no, I don't think that will work because the polyline might have multiple properties changed and the _propertiesChanged array in PolylineCollection still needs to be incremented.

[mramato]

Good call. That makes sense. Should we add a unit test for this?

@bagnell can you review and merge? Thanks.

[bagnell]

Looks good to me. Can you add a test @hpinkos?

[hpinkos]

@bagnell ready