No member extensions in the index

[ilya-g]

Describe the bug
The index page of Duration.Companion showing members:

The page of Duration.Companion.days:

As you can see, the member extension functions days are not displayed in the containing object members list.

Expected behaviour
Member extension functions are displayed in members list of the containing class/object.

[IgnatBeresnev]

Note: The problem might be in ExtensionExtractorTransformer