Some follow up tasks from enabling Parsoid Fragment support (T380758, T374616):

• Clean up old "no fragment" and "fragment v1" code in Parsoid\DataAccess and Parser.
• Instead of using Parser::mStripExtTags, introduce a new "output type". Right now the legacy parser uses $ot['html'] and Parsoid is using $ot['wt'] but we could introduce $ot['parsoid'] to replace the various Parsoid-specific booleans in Parser.
• Clean up https://gerrit.wikimedia.org/r/c/mediawiki/core/+/826408 and https://gerrit.wikimedia.org/r/c/mediawiki/extensions/Scribunto/+/826409 now that Parsoid and the legacy parser provide the same strip state
• Clean up https://gerrit.wikimedia.org/r/c/mediawiki/core/+/816086 -- this workaround may not be needed any more; instead we probably need to support passing fragments to/from the native Parsoid extension API. (This comes up with <syntaxhighlight><nowiki>foo</nowiki></syntaxhighlight> vs {{#tag:syntaxhighlight|<nowiki>foo</nowiki>}} .)