To achieve this we need to evaluate the DOM contents of
transclusion nodes to see if it consists solely of meta items
and whitespace.
To check for meta items we do a model registry match, but with an
additional parameter to exclude mwTransclusion types as a possible
result (as the first item may be a meta tag, but with a mw:Transclusion
typeof attribute).
Bug: 51322
Change-Id: I89a220350fb7e10e15f3682d21438539196a5846
