Fix StarBorder operator== (#113588)

dev/manual_tests/lib/star_border.dart

@@ -72,7 +72,6 @@ class _MyHomePageState extends State<MyHomePage> {
                 mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                 children: <Widget>[
                   Container(
-                    key: UniqueKey(),
                     alignment: Alignment.center,
                     width: 300,
                     height: 200,
@@ -94,7 +93,6 @@ class _MyHomePageState extends State<MyHomePage> {
                     child: const Text('Polygon'),
                   ),
                   Container(
-                    key: UniqueKey(),
                     alignment: Alignment.center,
                     width: 300,
                     height: 200,

examples/api/lib/painting/star_border/star_border.0.dart

@@ -144,7 +144,6 @@ class ExampleBorder extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return Container(
-      key: UniqueKey(),
       alignment: Alignment.center,
       padding: const EdgeInsets.all(20),
       width: 150,

packages/flutter/lib/src/painting/star_border.dart

@@ -422,7 +422,14 @@ class StarBorder extends OutlinedBorder {
     if (other.runtimeType != runtimeType) {
       return false;
     }
-    return other is StarBorder && other.side == side;
+    return other is StarBorder
+        && other.side == side
+        && other.points == points
+        && other._innerRadiusRatio == _innerRadiusRatio
+        && other.pointRounding == pointRounding
+        && other.valleyRounding == valleyRounding
+        && other._rotationRadians == _rotationRadians
+        && other.squash == squash;
   }
 
   @override