[css-images-4] Should `CSS.elementSources` be considered at risk?

[cdoublev]

Can you please clarify if you plan to drop CSS.elementSources? or even image()?

CSS.elementSources was hidden before #3572, which defined it with any as its type.

partial namespace CSS {
 [SameObject] readonly attribute any elementSources;
};

In #428, fixed by the above PR:

that spec version is way out of date and needs to get some stuff dropped.

If it should not be dropped, is there a reason to not define it as a maplike?

EXAMPLE 13

<script>
  var bg = document.createElement('canvas');
  CSS.elementSources.set('fancy', bg);
</script>