Should adopting from a Document into its associated inert template document (and vice versa) clear the adoptedStyleSheets? #133
Description
This came up on a recent Chromium bug. Currently adopting a shadow root with non-empty adoptedStyleSheets into a <template> document will clear the adoptedStyleSheets, and vice versa.
Say we have a Document X and it has a <template> element in it. The <template>'s contents' node document is the Document's associated-inert-template-document. This is a different Document than X, and adopting into or out of the <template>'s contents will clear the adoptedStyleSheets per our spec).
Maybe it's ok if we treat a Document and its associated-inert-template-document as the same document for adoptedStyleSheets related purposes, by adding a special case to the "adopting steps" to not clear adoptedStyleSheets if:
- The document we're adopting the node into is the same as the constructor document, or
- The document is an associated-inert-template-document of the constructor document.
And I think the constructor document will never be an associated-inert-template-document itself because that document is inert and shouldn't be able to construct stylesheets via script, but I might be wrong.
The main reasons we disallowed reusing constructed stylesheets on different documents are the concern that a constructed stylesheet from a document might keep the document alive, and different documents might have different fetch groups. I think this should be ok with the new addition. The <template>'s contents lifetime should be bounded by the document it is in, unless it gets adopted to a different document, in which case the adoptedStyleSheets will be cleared.