I am running on web and getting this error. Error: MissingPluginException(No implementation found for method close on channel flutter_webview_plugin)

## System info

Issue occurs on: WEB
Plugin version: latest
Flutter doctor output:

Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 2.0.0, on macOS 11.2.2 20D80 darwin-x64, locale en-PK)
[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.3)
[✓] Xcode - develop for iOS and macOS
[✓] Chrome - develop for the web
[✓] Android Studio (version 4.1)
[✓] Connected device (1 available)

• No issues found!

## Steps to Reproduce
Simply just run it on web and the page doesn't load and through an exception.

## Logs

[+4371 ms] Error: MissingPluginException(No implementation found for method close on channel flutter_webview_plugin)
at Object.throw_ [as throw] (http://localhost:53868/dart_sdk.js:5334:11)
at MethodChannel._invokeMethod (http://localhost:53868/packages/flutter/src/services/system_channels.dart.lib.js:954:21)
at _invokeMethod.next ()
at http://localhost:53868/dart_sdk.js:39032:33
at _RootZone.runUnary (http://localhost:53868/dart_sdk.js:38889:58)
at _FutureListener.thenAwait.handleValue (http://localhost:53868/dart_sdk.js:33875:29)
at handleValueCallback (http://localhost:53868/dart_sdk.js:34435:49)
at Function._propagateToListeners (http://localhost:53868/dart_sdk.js:34473:17)
at _Future.new.[_completeWithValue] (http://localhost:53868/dart_sdk.js:34315:23)
at async._AsyncCallbackEntry.new.callback (http://localhost:53868/dart_sdk.js:34338:35)
at Object._microtaskLoop (http://localhost:53868/dart_sdk.js:39176:13)
at _startMicrotaskLoop (http://localhost:53868/dart_sdk.js:39182:13)
at http://localhost:53868/dart_sdk.js:34689:9
[ +6 ms] Error: MissingPluginException(No implementation found for method launch on channel flutter_webview_plugin)
at Object.throw_ [as throw] (http://localhost:53868/dart_sdk.js:5334:11)
at MethodChannel._invokeMethod (http://localhost:53868/packages/flutter/src/services/system_channels.dart.lib.js:954:21)
at _invokeMethod.next ()
at http://localhost:53868/dart_sdk.js:39032:33
at _RootZone.runUnary (http://localhost:53868/dart_sdk.js:38889:58)
at _FutureListener.thenAwait.handleValue (http://localhost:53868/dart_sdk.js:33875:29)
at handleValueCallback (http://localhost:53868/dart_sdk.js:34435:49)
at Function._propagateToListeners (http://localhost:53868/dart_sdk.js:34473:17)
at _Future.new.[_completeWithValue] (http://localhost:53868/dart_sdk.js:34315:23)
at async._AsyncCallbackEntry.new.callback (http://localhost:53868/dart_sdk.js:34338:35)
at Object._microtaskLoop (http://localhost:53868/dart_sdk.js:39176:13)
at _startMicrotaskLoop (http://localhost:53868/dart_sdk.js:39182:13)
at http://localhost:53868/dart_sdk.js:34689:9

Start by reproducing the failure with Flutter 2.0.0 on the web and inspect how the plugin handles the close and launch methods on that platform. Done means the reported web page loads without MissingPluginException errors, with the required platform behavior defined and covered by an appropriate test.

Written by the indexing model from the issue text.