fix toString (#8688)

lib/ui/geometry.dart

@@ -879,7 +879,7 @@ class Rect {
   int get hashCode => hashValues(left, top, right, bottom);
 
   @override
-  String toString() => 'Rect.fromLTRB(${left.toStringAsFixed(1)} ${top.toStringAsFixed(1)}, ${right.toStringAsFixed(1)}, ${bottom.toStringAsFixed(1)})';
+  String toString() => 'Rect.fromLTRB(${left.toStringAsFixed(1)}, ${top.toStringAsFixed(1)}, ${right.toStringAsFixed(1)}, ${bottom.toStringAsFixed(1)})';
 }
 
 /// A radius for either circular or elliptical shapes.

testing/dart/rect_test.dart

@@ -7,6 +7,11 @@ import 'dart:ui';
 import 'package:test/test.dart';
 
 void main() {
+  test('toString test', () {
+    const Rect r = Rect.fromLTRB(1.0, 3.0, 5.0, 7.0);
+    expect(r.toString(), 'Rect.fromLTRB(1.0, 3.0, 5.0, 7.0)');
+  });
+
   test('rect accessors', () {
     const Rect r = Rect.fromLTRB(1.0, 3.0, 5.0, 7.0);
     expect(r.left, equals(1.0));