Fixes: "FloatingActionButton.extended's isExtended property if false should...

Fixes: "FloatingActionButton.extended's isExtended property if false should show icon, not label" (#72431)

* Fix extended FAB with isExtended set to false showing both icon and label

packages/flutter/lib/src/material/floating_action_button.dart

@@ -210,7 +210,11 @@ class FloatingActionButton extends StatelessWidget {
                  label,
                  const SizedBox(width: 20.0),
                ]
-             : <Widget>[
+             : !isExtended ? <Widget>[
+               const SizedBox(width: 20.0),
+               icon,
+               const SizedBox(width: 20.0),
+           ] : <Widget>[
                  const SizedBox(width: 16.0),
                  icon,
                  const SizedBox(width: 8.0),

packages/flutter/test/material/floating_action_button_test.dart

@@ -942,6 +942,27 @@ void main() {
       paints..circle(color: splashColor),
     );
   });
+
+  testWidgets('extended FAB does not show label when isExtended is false', (WidgetTester tester) async {
+    const Key iconKey = Key('icon');
+    const Key labelKey = Key('label');
+
+    await tester.pumpWidget(
+      Directionality(
+        textDirection: TextDirection.ltr,
+        child: FloatingActionButton.extended(
+          isExtended: false,
+          label: const Text('', key: labelKey),
+          icon: const Icon(Icons.add, key: iconKey),
+          onPressed: () {},
+        ),
+      ),
+    );
+
+    // Verify that Icon is present and label is not.
+    expect(find.byKey(iconKey), findsOneWidget);
+    expect(find.byKey(labelKey), findsNothing);
+  });
 }
 
 Offset _rightEdgeOfFab(WidgetTester tester) {