Prints a script to check whether or not the Customizer is supported,
and apply either the no-customize-support or customize-support class
to the body.

This function MUST be called inside the body tag.

Ideally, call this function immediately after the body tag is opened.
This prevents a flash of unstyled content.

It is also recommended that you add the “no-customize-support” class
to the body tag by default.

function wp_customize_support_script() {
	$admin_origin = parse_url( admin_url() );
	$home_origin  = parse_url( home_url() );
	$cross_domain = ( strtolower( $admin_origin['host'] ) != strtolower( $home_origin['host'] ) );
	$type_attr    = current_theme_supports( 'html5', 'script' ) ? '' : ' type="text/javascript"';
	?>