Bug 21078: overdrive.js Catch error if window.opener is not accessible

Bug 21078: overdrive.js Catch error if window.opener is not accessible

To Test:
0 - Enable overdrive search results on your koha
1 - From a source develop a link to your koha instance that opens a new
window:
<a target="_blank"
href="http://localhost:8080/cgi-bin/koha/opac-search.pl?q=love">Test</a>
2 - Click that link
3 - Note Overdrive results do not load
4 - Note error in JS console
5 - Apply patch
6 - Click the link again
7 - Note OD results load
8 - Note no error in console

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>