[analyzer] Handle NullAwareElements in Flutter outlines

Part of #56989

Change-Id: I32557d994d16b97b8f3b40bb3d654a657338b83e
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/411020
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Chloe Stefantsova <[email protected]>

Author: chloestefantsova

pkg/analysis_server/lib/src/flutter/flutter_outline_computer.dart

@@ -170,6 +170,8 @@ class FlutterOutlineComputer {
             // Ignored. It's possible that we might be able to extract
             // some information from some spread expressions, but it seems
             // unlikely enough that we're not handling it at the moment.
+          } else if (element is NullAwareElement) {
+            addChildrenFrom(element.value);
           }
         }
 

pkg/analysis_server/test/src/flutter/flutter_outline_computer_test.dart

@@ -355,6 +355,30 @@ class MyWidget extends StatelessWidget {
 ''');
   }
 
+  Future<void> test_children_withNullAwareElements() async {
+    var unitOutline = await _computeOutline('''
+import 'package:flutter/widgets.dart';
+
+class MyWidget extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return new Column(children: [
+      const Text('aaa'),
+      ?const Text('bbb'),
+    ]);
+  }
+}
+''');
+
+    expect(_toText(unitOutline), r'''
+(D) MyWidget
+  (D) build
+    Column
+      Text
+      Text
+''');
+  }
+
   Future<void> test_codeOffsetLength() async {
     var unitOutline = await _computeOutline('''
 import 'package:flutter/widgets.dart';