bugfix: Content disappears when function are messing around with ob_*

Calling functions should be pretty straight forward.
But we are doomed as soon as we rely on WordPress itself or Plugins
to end the OB-Caching-Levels properly.
Unfortunately we need to take care of this around the functions.

includes/internals.php

@@ -67,7 +67,13 @@ function _wp_twig_env_generic_delegate( Environment $environment ) {
 function _wp_twig_generic_delegate_target( $name ) {
 	if ( function_exists( $name ) ) {
 		return static function () use ( $name ) {
-			return call_user_func_array( $name, func_get_args() );
+			$level = ob_get_level();
+			$returnValue = call_user_func_array( $name, func_get_args() );
+			while (ob_get_level() > $level) {
+				ob_end_flush();
+			}
+
+			return $returnValue;
 		};
 	}