Add test cases from html5lib-tests tree-construction #5

Job	Run time
Core running from ${{ matrix.directory }}	0s
Gutenberg running from ${{ matrix.directory }}	0s
Core running from src / Core running from src / Linux	2m 5s
Core running from build / Core running from build / Linux	2m 6s
Core running from build / Core running from build / Windows	3m 39s
Core running from src / Core running from src / Windows	3m 34s
Gutenberg running from src / Gutenberg running from src / Linux	9m 55s
Gutenberg running from build / Gutenberg running from build / Linux	7m 47s
Gutenberg running from build / Gutenberg running from build / Windows	13m 57s
Gutenberg running from src / Gutenberg running from src / Windows	11m 44s
Slack Notifications	0s
Failed workflow tasks	0s
	54m 47s

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