analyzer: Change switch expression used as statement to statement

I'm not sure what our paradigm / style will be, but for now, we should
use a switch statement in this case, as I believe void-expressions in
switch-expressions are not allowed until Dart 3.1.0, and analyzer's
lower bound is still 3.0.0.

Change-Id: Ida7b9694cdaae2bd808caaa7f25c1063207e5bba
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/326245
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Samuel Rawlins <srawlins@google.com>
diff --git a/pkg/analyzer/lib/src/fasta/doc_comment_builder.dart b/pkg/analyzer/lib/src/fasta/doc_comment_builder.dart
index 6c786de..6dbe8d2 100644
--- a/pkg/analyzer/lib/src/fasta/doc_comment_builder.dart
+++ b/pkg/analyzer/lib/src/fasta/doc_comment_builder.dart
@@ -957,12 +957,12 @@
         return (positionalArguments, namedArguments);
       }
       var argument = _parseArgument();
-      // Remove when https://github.com/dart-lang/linter/issues/4361 is closed.
-      // ignore: unnecessary_parenthesis
-      (switch (argument) {
-        DocDirectivePositionalArgument() => positionalArguments.add(argument),
-        DocDirectiveNamedArgument() => namedArguments.add(argument),
-      });
+      switch (argument) {
+        case DocDirectivePositionalArgument():
+          positionalArguments.add(argument);
+        case DocDirectiveNamedArgument():
+          namedArguments.add(argument);
+      }
       index = _readWhitespace(content, index);
     }