(bug 65805) Fix notice when creating new filter

Notice: Undefined index: af_throttled in
extensions/AbuseFilter/Views/AbuseFilterViewEdit.php on line 148

This assumes af_throttled to exist in $newRow, which comes
from AbuseFilterViewEdit::loadRequest, which in turn comes
from AbuseFilterViewEdit::loadFilterData, where no
af_throttled property is added to the newly created object.

Bug: 65805
Change-Id: I45ad0ea2cea242711b6109e67b99b71242ff57f6
Merge "(bug 65805) Fix notice when creating new filter"