Revert "Add set semantics enabled API and wire iOS a11y bridge (#1612… (#165901)

…65)"

This reverts commit 26037dff87.

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PR causes internal test failures

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

@@ -28,7 +28,6 @@ mixin SemanticsBinding on BindingBase {
       ..onSemanticsActionEvent = _handleSemanticsActionEvent
       ..onAccessibilityFeaturesChanged = handleAccessibilityFeaturesChanged;
     _handleSemanticsEnabledChanged();
-    addSemanticsEnabledListener(_handleFrameworkSemanticsEnabledChanged);
   }
 
   /// The current [SemanticsBinding], if one has been created.
@@ -155,10 +154,6 @@ mixin SemanticsBinding on BindingBase {
     performSemanticsAction(decodedAction);
   }
 
-  void _handleFrameworkSemanticsEnabledChanged() {
-    platformDispatcher.setSemanticsTreeEnabled(semanticsEnabled);
-  }
-
   /// Called whenever the platform requests an action to be performed on a
   /// [SemanticsNode].
   ///

packages/flutter/test/semantics/semantics_binding_set_semantics_tree_enabled_test.dart

@@ -1,35 +0,0 @@
-// Copyright 2014 The Flutter Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-import 'dart:ui';
-
-import 'package:flutter_test/flutter_test.dart';
-
-void main() {
-  test('SemanticsHandle ensureSemantics calls setSemanticsTreeEnabled', () async {
-    final SemanticsTestBinding binding = SemanticsTestBinding();
-    expect(binding.platformDispatcher.semanticsTreeEnabled, isFalse);
-    final SemanticsHandle handle = binding.ensureSemantics();
-    expect(binding.platformDispatcher.semanticsTreeEnabled, isTrue);
-    handle.dispose();
-    expect(binding.platformDispatcher.semanticsTreeEnabled, isFalse);
-  });
-}
-
-class SemanticsTestBinding extends AutomatedTestWidgetsFlutterBinding {
-  @override
-  TestPlatformDispatcherSpy get platformDispatcher => _platformDispatcherSpy;
-  static final TestPlatformDispatcherSpy _platformDispatcherSpy = TestPlatformDispatcherSpy(
-    platformDispatcher: PlatformDispatcher.instance,
-  );
-}
-
-class TestPlatformDispatcherSpy extends TestPlatformDispatcher {
-  TestPlatformDispatcherSpy({required super.platformDispatcher});
-  bool semanticsTreeEnabled = false;
-  @override
-  void setSemanticsTreeEnabled(bool enabled) {
-    semanticsTreeEnabled = enabled;
-  }
-}