Fix RenderFlex's baseline calculation with verticalDirection.up and Axis.vertical

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

@@ -680,10 +680,7 @@ class RenderFlex extends RenderBox with ContainerRenderObjectMixin<RenderBox, Fl
 
   @override
   double? computeDistanceToActualBaseline(TextBaseline baseline) {
-    return switch (_direction) {
-      Axis.horizontal => defaultComputeDistanceToHighestActualBaseline(baseline),
-      Axis.vertical   => defaultComputeDistanceToFirstActualBaseline(baseline),
-    };
+    return defaultComputeDistanceToHighestActualBaseline(baseline);
   }
 
   static int _getFlex(RenderBox child) {

packages/flutter/test/rendering/flex_test.dart

@@ -648,6 +648,45 @@ void main() {
     expect(box2.localToGlobal(Offset.zero).dy, 0.0);
   });
 
+  test('Vertical Flex Baseline', () {
+    const BoxConstraints square = BoxConstraints.tightFor(width: 100.0, height: 100.0);
+    final RenderConstrainedBox box1 = RenderConstrainedBox(
+      additionalConstraints: square,
+      child: RenderFlowBaselineTestBox()
+        ..gridCount = 1
+        ..baselinePlacer = (double height) => 10,
+    );
+    final RenderConstrainedBox box2 = RenderConstrainedBox(
+      additionalConstraints: square,
+      child: RenderFlowBaselineTestBox()
+        ..gridCount = 1
+        ..baselinePlacer = (double height) => 10,
+    );
+    final RenderFlex flex = RenderFlex(
+      textDirection: TextDirection.ltr,
+      children: <RenderBox>[box1, box2],
+      direction: Axis.vertical,
+    );
+    layout(flex, phase: EnginePhase.paint);
+
+    // We can't call the getDistanceToBaseline method directly. Check the dry
+    // baseline instead, and in debug mode there are asserts that verify
+    // the two methods return the same results.
+    expect(flex.getDryBaseline(flex.constraints, TextBaseline.alphabetic), 10);
+
+    flex.mainAxisAlignment = MainAxisAlignment.end;
+    pumpFrame(phase: EnginePhase.paint);
+    expect(flex.getDryBaseline(flex.constraints, TextBaseline.alphabetic), 410);
+
+    flex.verticalDirection = VerticalDirection.up;
+    pumpFrame(phase: EnginePhase.paint);
+    expect(flex.getDryBaseline(flex.constraints, TextBaseline.alphabetic), 10);
+
+    flex.mainAxisAlignment = MainAxisAlignment.start;
+    pumpFrame(phase: EnginePhase.paint);
+    expect(flex.getDryBaseline(flex.constraints, TextBaseline.alphabetic), 410);
+  });
+
   group('Intrinsics', () {
     test('main axis intrinsics with RenderAspectRatio 1', () {
       const BoxConstraints square = BoxConstraints.tightFor(width: 100.0, height: 100.0);