Defer the preview starting to listen to setting changes until after the Customizer has synced settings into the preview. This ensures that any differences between the JS and PHP representations of the settings won't cause an infinite refresh.
See #32911.
Fixes#32894.
Built from https://develop.svn.wordpress.org/trunk@33134
git-svn-id: http://core.svn.wordpress.org/trunk@33105 1a063a9b-81f0-0310-95a4-ce76da25c4cd