[9] RFR for 8151269: [TEST] add test covering getSource() method for multiresolution image

[Alexander Stepanov]

Hello,

Could you please review the following fix
http://cr.openjdk.java.net/~avstepan/8151269/webrev.00/
for
https://bugs.openjdk.java.net/browse/JDK-8151269 ?

Just a single test added.

Thanks,
Alexander