simulatedAccessibilityTraversal account for force merging (#135178)

fixes https://github.com/flutter/flutter/issues/135144

packages/flutter_test/lib/src/controller.dart

@@ -242,23 +242,29 @@ class SemanticsController {
   /// * [flutter/engine/AccessibilityBridge.java#SemanticsNode.isFocusable()](https://github.com/flutter/engine/blob/main/shell/platform/android/io/flutter/view/AccessibilityBridge.java#L2641)
   /// * [flutter/engine/SemanticsObject.mm#SemanticsObject.isAccessibilityElement](https://github.com/flutter/engine/blob/main/shell/platform/darwin/ios/framework/Source/SemanticsObject.mm#L449)
   bool _isImportantForAccessibility(SemanticsNode node) {
+    if (node.isMergedIntoParent) {
+      // If this node is merged, all its information are present on an ancestor
+      // node.
+      return false;
+    }
+    final SemanticsData data = node.getSemanticsData();
     // If the node scopes a route, it doesn't matter what other flags/actions it
     // has, it is _not_ important for accessibility, so we short circuit.
-    if (node.hasFlag(SemanticsFlag.scopesRoute)) {
+    if (data.hasFlag(SemanticsFlag.scopesRoute)) {
       return false;
     }
 
-    final bool hasNonScrollingAction = node.getSemanticsData().actions & ~_scrollingActions != 0;
+    final bool hasNonScrollingAction = data.actions & ~_scrollingActions != 0;
     if (hasNonScrollingAction) {
       return true;
     }
 
-    final bool hasImportantFlag = node.getSemanticsData().flags & _importantFlagsForAccessibility != 0;
+    final bool hasImportantFlag = data.flags & _importantFlagsForAccessibility != 0;
     if (hasImportantFlag) {
       return true;
     }
 
-    final bool hasContent = node.label.isNotEmpty || node.value.isNotEmpty || node.hint.isNotEmpty;
+    final bool hasContent = data.label.isNotEmpty || data.value.isNotEmpty || data.hint.isNotEmpty;
     if (hasContent) {
       return true;
     }

packages/flutter_test/test/controller_test.dart

@@ -982,6 +982,38 @@ void main() {
           tester.semantics.simulatedAccessibilityTraversal(),
           containsAllInOrder(expectedMatchers));
       });
+
+      testWidgets('merging node should not be visited', (WidgetTester tester) async {
+        await tester.pumpWidget(
+          MaterialApp(
+            home: MergeSemantics(
+              child: Column(
+                children: <Widget>[
+                  Semantics(
+                    container: true,
+                    child: const Text('1'),
+                  ),
+                  Semantics(
+                    container: true,
+                    child: const Text('2'),
+                  ),
+                  Semantics(
+                    container: true,
+                    child: const Text('3'),
+                  ),
+                ],
+              ),
+            ),
+          ),
+        );
+
+        expect(
+          tester.semantics.simulatedAccessibilityTraversal(),
+          orderedEquals(
+            <Matcher>[containsSemantics(label: '1\n2\n3')],
+          ),
+        );
+      });
     });
   });
 }