Update image_test.dart

Author: dkwingsmt

lib/web_ui/test/html/image_test.dart

@@ -76,7 +76,7 @@ Future<Image> _encodeToHtmlThenDecode(
 // current Web engine decodes pixel data.
 //
 // The HTML renderer uses the BMP format to display pixel data, but it used to
-// uses a wrong implementation. The bug has been fixed, but the fix breaks apps
+// use a wrong implementation. The bug has been fixed, but the fix breaks apps
 // that had to provide incorrect data to work around this issue. This function
 // is used in the migration guide to assist libraries that would like to run on
 // both pre- and post-patch engines by testing the current behavior on a single