Fix samples metadata concat.

<?cs # generate metadata file for samples only ?><?cs

if:samples_only ?>METADATA['<?cs var:metadata.lang ?>'].develop = METADATA['<?cs var:metadata.lang ?>'].develop.concat([

<?cs var:reference_tree ?>

];

]);

<?cs # generate standard unified metadata file ?><?cs

else ?>window.METADATA = window.METADATA || {};

METADATA['<?cs var:metadata.lang ?>'] = {};