wpView: consolidate pausePlayers() and unsetPlayers(), they are almost the same. Prevent errors when instead of a player ME.js shows only a "Download File" placeholder (in IE). See #28905.
Built from https://develop.svn.wordpress.org/trunk@29272


git-svn-id: http://core.svn.wordpress.org/trunk@29054 1a063a9b-81f0-0310-95a4-ce76da25c4cd
wpView: make sure the editor is focused before selecting/deselecting a view, or IE may throw an invalid range error, see #28595.
Built from https://develop.svn.wordpress.org/trunk@29273


git-svn-id: http://core.svn.wordpress.org/trunk@29055 1a063a9b-81f0-0310-95a4-ce76da25c4cd