As of http://trac.webkit.org/changeset/79799 (unless it gets rolled out), we are showing XML Viewer for XML files that have no style information associated with them. It is partially implemented in the XML parser and hence requires special handling for Qt. I'll mute the tests for now.
http://trac.webkit.org/changeset/89516 introduced a build flag for Qt to use libxml2 and libxslt. (Supported only on Linux for now).
If we turn that flag on, we will pass these tests.
libxml2 and libxslt are default long time ago ( https://trac.webkit.org/changeset/114240 ) So these tests pass, and I unskipped them - https://trac.webkit.org/changeset/129301
But xmlviewer/extensions-api.html fails on Qt WK1 (passes on WK2),
so I filed a new bug report about it - https://bugs.webkit.org/show_bug.cgi?id=97389