Add role check in SemanticsNode._isDifferentFromCurrentSemanticAnnotation function. (#162578)

Fixes https://github.com/flutter/flutter/issues/162577

### Description
- Adds `role` check in
`SemanticsNode._isDifferentFromCurrentSemanticAnnotation` function.
- Adds `SemanticsNode.debugIsDirty` property to check in tests whether
the node is marked as dirty.

## Pre-launch Checklist

- [X] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [X] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [X] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [X] I signed the [CLA].
- [X] I listed at least one issue that this PR fixes in the description
above.
- [ ] I updated/added relevant documentation (doc comments with `///`).
- [X] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [X] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [X] All existing and new tests are passing.

packages/flutter/lib/src/semantics/semantics.dart

@@ -2429,6 +2429,22 @@ class SemanticsNode with DiagnosticableTreeMixin {
     }
   }
 
+  /// When asserts are enabled, returns whether node is marked as dirty.
+  ///
+  /// Otherwise, returns null.
+  ///
+  /// This getter is intended for use in framework unit tests. Applications must
+  /// not depend on its value.
+  @visibleForTesting
+  bool? get debugIsDirty {
+    bool? isDirty;
+    assert(() {
+      isDirty = _dirty;
+      return true;
+    }());
+    return isDirty;
+  }
+
   bool _isDifferentFromCurrentSemanticAnnotation(SemanticsConfiguration config) {
     return _attributedLabel != config.attributedLabel ||
         _attributedHint != config.attributedHint ||
@@ -2454,7 +2470,7 @@ class SemanticsNode with DiagnosticableTreeMixin {
         _areUserActionsBlocked != config.isBlockingUserActions ||
         _headingLevel != config._headingLevel ||
         _linkUrl != config._linkUrl ||
-        _linkUrl != config._linkUrl;
+        _role != config.role;
   }
 
   // TAGS, LABELS, ACTIONS

packages/flutter/test/semantics/semantics_test.dart

@@ -464,6 +464,19 @@ void main() {
         expect(root.debugSemantics!.getSemanticsData().actions, expectedActions);
       },
     );
+
+    test('updateWith marks node as dirty when role changes', () {
+      final SemanticsNode node = SemanticsNode();
+
+      expect(node.role, SemanticsRole.none);
+      expect(node.debugIsDirty, isFalse);
+
+      final SemanticsConfiguration config = SemanticsConfiguration()..role = SemanticsRole.tab;
+      node.updateWith(config: config);
+
+      expect(node.role, config.role);
+      expect(node.debugIsDirty, isTrue);
+    });
   });
 
   test('toStringDeep() does not throw with transform == null', () {