Fix external JS type option logic

The following conditional checks if the $mod_base_url exists anywhere within the external js file path, rather than the actual base url of the filepath, which returns true for a url such as http://my.externaldomain.com/foo/{mod_base_url}/path/to/file.js, which is incorrect.

      // If type is external and starts with http, https, or // but points to
      // this host change to file, but move it to the top of the aggregation
      // stack.
      if ($value['type'] === 'external'
        && stripos($value['data'], $mod_base_url) !== FALSE
        && (stripos($value['data'], 'http://') === 0
          || stripos($value['data'], 'https://') === 0
          || strpos($value['data'], '//') === 0
          )
      ) {

This should be validating that the $mod_base_url is actually the base url to the resource, and not just contained anywhere within $value['data'].

Suggested fix:

      // If type is external and starts with http, https, or // but points to
      // this host change to file, but move it to the top of the aggregation
      // stack.
      if ($value['type'] === 'external'
        && preg_match('#^(https?:)?//' . preg_quote($mod_base_url) . '#i', $value['data']) === 1
      ) {