Breaks parse_server_sdk (no idea who's fault it is)

[sgehrman]

The argument type 'WebSocket (where WebSocket is defined in /home/steve/development/flutter/bin/cache/dart-sdk/lib/html/dart2js/html_dart2js.dart)' can't be assigned to the parameter type 'WebSocket (where WebSocket is defined in /home/steve/.pub-cache/hosted/pub.dev/web-0.4.0/lib/src/dom/websockets.dart)'.

[sgehrman]

2.4.2 all of a sudden broke my app.

[sgehrman]

parse-community/Parse-SDK-Flutter#985

[sgehrman]

also getting:

../../../../../.pub-cache/hosted/pub.dev/web_socket_channel-2.4.2/lib/src/web_helpers.dart:10:32:
Error: The getter 'EventStreamProviders' isn't defined for the class 'WebSocket'.
 - 'WebSocket' is from 'package:web/src/dom/websockets.dart' ('../../../../../.pub-cache/hosted/pub.dev/web-0.3.0/lib/src/dom/websockets.dart').
  Stream<Event> get onOpenX => EventStreamProviders.openEvent.forTarget(this);
                               ^^^^^^^^^^^^^^^^^^^^
../../../../../.pub-cache/hosted/pub.dev/web_socket_channel-2.4.2/lib/src/web_helpers.dart:12:7:
Error: The getter 'EventStreamProviders' isn't defined for the class 'WebSocket'.
 - 'WebSocket' is from 'package:web/src/dom/websockets.dart' ('../../../../../.pub-cache/hosted/pub.dev/web-0.3.0/lib/src/dom/websockets.dart').
      EventStreamProviders.messageEvent.forTarget(this);
      ^^^^^^^^^^^^^^^^^^^^
../../../../../.pub-cache/hosted/pub.dev/web_socket_channel-2.4.2/lib/src/web_helpers.dart:14:7:
Error: The getter 'EventStreamProviders' isn't defined for the class 'WebSocket'.
 - 'WebSocket' is from 'package:web/src/dom/websockets.dart' ('../../../../../.pub-cache/hosted/pub.dev/web-0.3.0/lib/src/dom/websockets.dart').
      EventStreamProviders.closeEvent.forTarget(this);
      ^^^^^^^^^^^^^^^^^^^^
../../../../../.pub-cache/hosted/pub.dev/web_socket_channel-2.4.2/lib/src/web_helpers.dart:16:7:
Error: The getter 'EventStreamProviders' isn't defined for the class 'WebSocket'.
 - 'WebSocket' is from 'package:web/src/dom/websockets.dart' ('../../../../../.pub-cache/hosted/pub.dev/web-0.3.0/lib/src/dom/websockets.dart').
      EventStreamProviders.errorEventSourceEvent.forTarget(this);
      ^^^^^^^^^^^^^^^^^^^^
Error: Compilation failed.
  Command: /home/steve/development/flutter/bin/cache/dart-sdk/bin/dart --disable-dart-dev /home/steve/development/flutter/bin/cache/dart-sdk/bin/snapshots/dart2js.dart.snapshot
  --platform-binaries=/home/steve/development/flutter/bin/cache/flutter_web_sdk/kernel --invoker=flutter_tool -Ddart.vm.product=true -DFLUTTER_WEB_AUTO_DETECT=false -DFLUTTER_WEB_USE_SKIA=false
  -DFLUTTER_WEB_CANVASKIT_URL=https://www.gstatic.com/flutter-canvaskit/3f3e560236539b7e2702f5ac790b2a4691b32d49/ --native-null-assertions --no-source-maps -o
  /home/steve/Documents/GitHub/dfc/dashboard/extension_ui/.dart_tool/flutter_build/ed1db08d1f76e474e7c42ea30f371a6b/app.dill --packages=.dart_tool/package_config.json --cfe-only
  /home/steve/Documents/GitHub/dfc/dashboard/extension_ui/.dart_tool/flutter_build/ed1db08d1f76e474e7c42ea30f371a6b/main.dart

[devoncarew]

De-duping this issue with #318.