* There's a branch path in the sanitizer that depends on $wgUseTidy,
which means the test output differs from on wiki.
* In general, we should set these variables to match the wiki behaviour
in tests.
* Exposes T92892, Sanitizer removes empty tags when tidy is disabled.
* Tweaked tests for T19663 to use an extension tag to show that
HTML5 tags with non-word characters make it through the parser
intact (before being ultimately sanitized).
Change-Id: I09c72fd739e11a8b757f37dc4c790758d782ad73
78c3f2f4b1