narrow [nfc]: Inline away TopicNarrow.processTopicLikeServer

This will help us move the underlying logic to live on a substore,
which in turn will let us save these advance lookups and the annoying
zulipFeatureLevel conditional.

Author: gnprice

lib/model/narrow.dart

@@ -108,24 +108,6 @@ class TopicNarrow extends Narrow implements SendableNarrow {
 
   TopicNarrow sansWith() => TopicNarrow(streamId, topic);
 
-  /// Process [topic] to match how it would appear on a message object from
-  /// the server.
-  ///
-  /// Returns a new [TopicNarrow] with the [topic] processed.
-  ///
-  /// See [TopicName.processLikeServer].
-  TopicNarrow processTopicLikeServer({
-    required int zulipFeatureLevel,
-    required String? realmEmptyTopicDisplayName,
-  }) {
-    return TopicNarrow(
-      streamId,
-      topic.processLikeServer(
-        zulipFeatureLevel: zulipFeatureLevel,
-        realmEmptyTopicDisplayName: realmEmptyTopicDisplayName),
-      with_: with_);
-  }
-
   @override
   bool containsMessage(MessageBase message) {
     final conversation = message.conversation;

lib/widgets/message_list.dart

@@ -774,14 +774,16 @@ class _MessageListState extends State<MessageList> with PerAccountStoreAwareStat
   }
 
   void _initModel(PerAccountStore store, Anchor anchor) {
-    // Normalize topic name if this is a TopicNarrow. See #1717.
     var narrow = widget.narrow;
     if (narrow is TopicNarrow) {
-      narrow = narrow.processTopicLikeServer(
-        zulipFeatureLevel: store.zulipFeatureLevel,
-        realmEmptyTopicDisplayName: store.zulipFeatureLevel > 334
-          ? store.realmEmptyTopicDisplayName
-          : null);
+      // Normalize topic name.  See #1717.
+      narrow = TopicNarrow(narrow.streamId,
+        narrow.topic.processLikeServer(
+          zulipFeatureLevel: store.zulipFeatureLevel,
+          realmEmptyTopicDisplayName: store.zulipFeatureLevel > 334
+            ? store.realmEmptyTopicDisplayName
+            : null),
+        with_: narrow.with_);
       if (narrow != widget.narrow) {
         SchedulerBinding.instance.scheduleFrameCallback((_) {
           widget.onNarrowChanged(narrow);