test thead / tfooter contains th elements

test thead / tfooter contains th elements

Implemented by r85922. Cover r85943.

TEST PLAN:

$ php parserTests.php --regex 'Table have th inside t'
This is MediaWiki version 1.19alpha (r89594).

Reading tests from "tests/parser/parserTests.txt"...
Running test Table have th inside tfoot... PASSED
Running test Table have th inside thead... PASSED

Reading tests from "tests/parser/extraParserTests.txt"...

Reading tests from "../mwexts/LabeledSectionTransclusion/lstParserTests.txt"...

Passed 2 of 2 tests (100%)... ALL TESTS PASSED!
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