[file_selector_web] Listens to file input cancel event.#3683

auto-submit[bot] merged 13 commits into

flutter:mainflutter/packages:mainfrom

raju-muliyashiya:fix_file_selector_web_returns_null_on_presses_cancelraju-muliyashiya/flutter_packages:fix_file_selector_web_returns_null_on_presses_cancelCopy head branch name to clipboard