Bump happy-dom from 14.12.3 to 16.6.0 #967

Job	Run time
lint	3m 13s
unit_tests (16)	1m 43s
unit_tests (18)	1m 32s
crossbrowser_and_umd_unit_tests	2m 53s
unit_tests (20)	1m 28s
unit_tests (22)	1m 27s
integration_tests / test	1s
fullstack_production_suite / test	1s
lint_markdown_files / lint	57s
Coveralls coverage	4s
	13m 19s

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