Add final newline to sdk_labels.json file.

Rewrite generating script to use `async` features.

Author: lrhn

static/sdk_labels.json

@@ -13,6 +13,7 @@
  "analyzer-data-driven-fixes",
  "analyzer-editing-experience",
  "analyzer-hint",
+ "analyzer-language-patterns",
  "analyzer-linter",
  "analyzer-lsp",
  "analyzer-package",
@@ -149,6 +150,7 @@
  "fe-analyzer-shared-field-promotion",
  "fe-analyzer-shared-flow-analysis",
  "fe-analyzer-shared-parser",
+ "fe-analyzer-shared-parser-recovery",
  "front-end-analyzer-unification",
  "front-end-cleanup",
  "front-end-directive-listener",
@@ -270,4 +272,4 @@
  "web-triage-0",
  "web-triage-1",
  "web-triage-2"
-]
+]

tool/update_sdk_labels.dart

@@ -11,14 +11,12 @@ Future<void> main() async {
   final gitHub = GitHub();
 
   try {
-    final labels = await gitHub.issues
-        .listLabels(RepositorySlug('dart-lang', 'sdk'))
-        .toList();
-
-    final labelValues = labels.map((label) => label.name).toList();
+    final sdkLabelRequest =
+        gitHub.issues.listLabels(RepositorySlug('dart-lang', 'sdk'));
+    final labelNames = [await for (var label in sdkLabelRequest) label.name];
 
     File('static/sdk_labels.json').writeAsStringSync(
-      const JsonEncoder.withIndent(' ').convert(labelValues),
+      '${const JsonEncoder.withIndent(' ').convert(labelNames)}\n',
     );
   } finally {
     gitHub.dispose();