With IE11 no longer supported, the primary problem with assistive technology support for native HTML5 elements no longer applies.
This commit removes the `role` attribute from the following HTML5 elements with default landmark roles, per formerly required role attributes and W3C.
Follow-up to [17669], [21261], [23452], [24832], [29892], [38833], [40851], [43842], [46271], [49216].
Props costdev, craigfrancis, joedolson, mukesh27, ryokuhi, sabernhardt.
Fixes#54079.
Built from https://develop.svn.wordpress.org/trunk@52013
git-svn-id: http://core.svn.wordpress.org/trunk@51604 1a063a9b-81f0-0310-95a4-ce76da25c4cd