Remove commented-out code in ArgumentDefaultTest referring to php module

There are 3 classes named ArgumentDefaultTest in different namespaces, updated the IS to include the namespace of the class in question.

The todo was added to views contrib in 6a809c28 in February 2010. I think that was back in the bad old days of php.module. I think we can removed this.

@mstrelan, thanks for the link. Yes, this does look like it was for testing with the php module. I agree it is safe to delete.

Adding parent and updating IS and title.

Committed/pushed to 11.x and cherry-picked back through to 10.3.x, thanks!

catch → closed merge request !8452

Restoring @catch's credit.