(bug 44744) Site links table: Attaching table headers earlier

Attach the headers before initializing a new (first) value in order to not have the license
information tooltip appear in the wrong spot. (The new value's table row would be shifted
after adding the headers.)

Change-Id: Id90d782a6d70b9e1e716a44345ceff6d89efb7bc
Merge "(bug 44744) Site links table: Attaching table headers earlier"