fix missing license

Author: mdebbar

ci/licenses_golden/licenses_flutter

@@ -490,6 +490,7 @@ FILE: ../../../flutter/lib/web_ui/lib/src/engine/text_editing/text_editing.dart
 FILE: ../../../flutter/lib/web_ui/lib/src/engine/util.dart
 FILE: ../../../flutter/lib/web_ui/lib/src/engine/validators.dart
 FILE: ../../../flutter/lib/web_ui/lib/src/engine/vector_math.dart
+FILE: ../../../flutter/lib/web_ui/lib/src/engine/web_experiments.dart
 FILE: ../../../flutter/lib/web_ui/lib/src/engine/window.dart
 FILE: ../../../flutter/lib/web_ui/lib/src/ui/canvas.dart
 FILE: ../../../flutter/lib/web_ui/lib/src/ui/channel_buffers.dart