Fix analyzer issue.

Author: eyebrowsoffire

lib/web_ui/lib/src/engine/html/dom_canvas.dart

@@ -11,7 +11,6 @@ import 'package:ui/ui.dart' as ui;
 
 import '../browser_detection.dart';
 import '../engine_canvas.dart';
-import '../html_image_codec.dart';
 import '../text/canvas_paragraph.dart';
 import '../util.dart';
 import '../vector_math.dart';