Customize: Fix PHP notice when calling `WP_Customize_Control::json()` inside `content_template()` method.

A `temp` control is instantiated when `WP_Customize_Manager:: render_control_templates()` is called. This control needs to explicitly specify an empty settings array to avoid trying to use a `temp` setting which won't exist.

See #35926.
See #29572.


git-svn-id: https://develop.svn.wordpress.org/trunk@36776 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-customize-manager.php

@@ -1401,7 +1401,9 @@ final class WP_Customize_Manager {
 	 */
 	public function render_control_templates() {
 		foreach ( $this->registered_control_types as $control_type ) {
-			$control = new $control_type( $this, 'temp', array() );
+			$control = new $control_type( $this, 'temp', array(
+				'settings' => array(),
+			) );
 			$control->print_template();
 		}
 	}