Remove unused import.

Author: eyebrowsoffire

lib/web_ui/test/ui/image_golden_test.dart

@@ -11,7 +11,6 @@ import 'dart:typed_data';
 import 'package:test/bootstrap/browser.dart';
 import 'package:test/test.dart';
 import 'package:ui/src/engine.dart';
-import 'package:ui/src/engine/canvaskit/canvaskit_api.dart';
 
 import 'package:ui/ui.dart' as ui;
 import 'package:web_engine_tester/golden_tester.dart';