Reenable support for LIC on structured grids.

Since we created a new representation for structured grids, we needed to
ensure that the LIC representation extended that new representation as
well. This fixes the lack of surface lic representations when structured
grid datasets were loaded.

Change-Id: I906e0dc370d9731b45b993b0b56689e719d44fca
Merge topic 'fix_lic_on_structured_grids' into next

26f8bf43 Reenable support for LIC on structured grids.