Changeset 31329 for trunk/tests/phpunit/tests/customize/manager.php

Ensure that WP_Customize_Setting::value() returns default value for setting if not dirty.

There was regression introduced by #28580 where only changed (dirty) settings now are POST'ed to the Customizer preview.

• Allow WP_Customize_Manager::post_value() to accept a second $default argument.
• Introduce WP_Customize_Manager::unsanitized_post_values() for accessing previously-private member variable _post_values.
• Do require_once instead of require for Customizer classes.
• Add unit tests for WP_Customize_Manager and WP_Customize_Setting.

props westonruter.
fixes #30988.