Remove trailing whitespace from [27982].
Built from https://develop.svn.wordpress.org/trunk@27984


git-svn-id: http://core.svn.wordpress.org/trunk@27814 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Widget Customizer: Move `WidgetCustomizer` to `wp.customize.Widgets`. First pass.

see #27690.
Built from https://develop.svn.wordpress.org/trunk@27985


git-svn-id: http://core.svn.wordpress.org/trunk@27815 1a063a9b-81f0-0310-95a4-ce76da25c4cd