Moves the repeated code in the emoji browser support test to a function to reduced the potential for errors and follow DRY principles.
Renames the "emoji4" test "emoji" as unicode version specific tests were removed in [38869].
Props peterwilsoncc, pento for code review.
Fixes#41156.
Built from https://develop.svn.wordpress.org/trunk@41669
git-svn-id: http://core.svn.wordpress.org/trunk@41503 1a063a9b-81f0-0310-95a4-ce76da25c4cd