Re-enables tests previously failing due to new semantics flag. (#66916)

packages/flutter/lib/src/rendering/custom_paint.dart

@@ -838,6 +838,9 @@ class RenderCustomPaint extends RenderProxyBox {
     if (properties.textField != null) {
       config.isTextField = properties.textField!;
     }
+    if (properties.slider != null) {
+      config.isSlider = properties.slider!;
+    }
     if (properties.readOnly != null) {
       config.isReadOnly = properties.readOnly!;
     }

packages/flutter/test/widgets/custom_painter_test.dart

@@ -501,7 +501,7 @@ void _defineTests() {
     );
     expect(semantics, hasSemantics(expectedSemantics, ignoreRect: true, ignoreTransform: true));
     semantics.dispose();
-  }, skip: true); // TODO(abrusher): Enable once engine PR #20385 lands.
+  });
 
   group('diffing', () {
     testWidgets('complains about duplicate keys', (WidgetTester tester) async {

packages/flutter/test/widgets/semantics_test.dart

@@ -541,7 +541,7 @@ void main() {
 
     expect(semantics, hasSemantics(expectedSemantics, ignoreId: true));
     semantics.dispose();
-  }, skip: true); // TODO(abrusher): Enable once engine PR #20385 lands.
+  });
 
   testWidgets('Actions can be replaced without triggering semantics update', (WidgetTester tester) async {
     final SemanticsTester semantics = SemanticsTester(tester);

packages/flutter_test/lib/src/matchers.dart

@@ -449,6 +449,7 @@ Matcher matchesSemantics({
   bool isChecked = false,
   bool isSelected = false,
   bool isButton = false,
+  bool isSlider = false,
   bool isLink = false,
   bool isFocused = false,
   bool isFocusable = false,
@@ -468,7 +469,6 @@ Matcher matchesSemantics({
   bool hasToggledState = false,
   bool isToggled = false,
   bool hasImplicitScrolling = false,
-  bool isSlider = false,
   // Actions //
   bool hasTapAction = false,
   bool hasLongPressAction = false,
@@ -501,6 +501,7 @@ Matcher matchesSemantics({
     if (isChecked) SemanticsFlag.isChecked,
     if (isSelected) SemanticsFlag.isSelected,
     if (isButton) SemanticsFlag.isButton,
+    if (isSlider) SemanticsFlag.isSlider,
     if (isLink) SemanticsFlag.isLink,
     if (isTextField) SemanticsFlag.isTextField,
     if (isReadOnly) SemanticsFlag.isReadOnly,

packages/flutter_test/test/matchers_test.dart

@@ -573,6 +573,7 @@ void main() {
          isChecked: true,
          isSelected: true,
          isButton: true,
+         isSlider: true,
          isLink: true,
          isTextField: true,
          isReadOnly: true,
@@ -616,7 +617,7 @@ void main() {
          hasDismissAction: true,
          customActions: <CustomSemanticsAction>[action],
       ));
-    }, skip: true); // TODO(abrusher): Enable once engine PR #20385 lands.
+    });
 
     testWidgets('Can match child semantics', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();