Steps to Reproduce

1. Open an text field on Flutter Web
2. Enter text to the field
3. Right click and select "select all"
4. Select all won't select the text

Solution

Currently Flutter Web Engine uses the following handlers to track selection changes:

https://github.com/nturgut/engine/blob/20544a0a66588ec56cc43742e08ee943c037984a/lib/web_ui/lib/src/engine/text_editing.dart#L323

We should also add domElement.onSelect for Firefox.