wip make dividers black

Author: gnprice

lib/widgets/message_list.dart

@@ -485,14 +485,14 @@ class DateSeparator extends StatelessWidget {
       child: Padding(
         padding: const EdgeInsets.symmetric(vertical: 8, horizontal: 2),
         child: Row(children: [
-          Expanded(
+          const Expanded(
             child: SizedBox(height: 0,
               child: DecoratedBox(
                 decoration: BoxDecoration(
                   border: Border(
                     bottom: BorderSide(
                       width: 0,
-                      color: color)))))),
+                      color: Colors.black)))))),
           Padding(padding: const EdgeInsets.symmetric(horizontal: 2),
             // TODO dedupe with RecipientHeaderDate
             child: Text(
@@ -512,13 +512,13 @@ class DateSeparator extends StatelessWidget {
                 zulipLocalizations,
                 DateTime.fromMillisecondsSinceEpoch(message.timestamp * 1000),
                 now: DateTime.now()))),
-          SizedBox(height: 0, width: 12,
+          const SizedBox(height: 0, width: 12,
             child: DecoratedBox(
               decoration: BoxDecoration(
                 border: Border(
                   bottom: BorderSide(
                     width: 0,
-                    color: color)))))
+                    color: Colors.black)))))
         ])),
     );
   }