title: Error: Method not found: 'allowInterop'. when trying to use any firebase app
body: <p>I am trying to create a web app that depends on firebase apps. The app runs if no firebase dependencies are added. Once I add the apps the app fails to build and run with this error:</p>
  <pre><code>lib\main.dart:1
  /C:/src/flutter/packages/flutter_web_plugins/lib/src/navigation/js_url_strategy.dart:44:14: Error: Method not found: 'allowInterop'.
      getPath: allowInterop(strategy.getPath),
               ^^^^^^^^^^^^
  /C:/src/flutter/packages/flutter_web_plugins/lib/src/navigation/js_url_strategy.dart:45:15: Error: Method not found: 'allowInterop'.
      getState: allowInterop(strategy.getState),
                ^^^^^^^^^^^^
  /C:/src/flutter/packages/flutter_web_plugins/lib/src/navigation/js_url_strategy.dart:46:26: Error: Method not found: 'allowInterop'.
  
      addPopStateListener: allowInterop(strategy.addPopStateListener),
                           ^^^^^^^^^^^^
  /C:/src/flutter/packages/flutter_web_plugins/lib/src/navigation/js_url_strategy.dart:47:25: Error: Method not found: 'allowInterop'.
      prepareExternalUrl: allowInterop(strategy.prepareExternalUrl),
                          ^^^^^^^^^^^^
  /C:/src/flutter/packages/flutter_web_plugins/lib/src/navigation/js_url_strategy.dart:48:16: Error: Method not found: 'allowInterop'.
      pushState: allowInterop(strategy.pushState),
                 ^^^^^^^^^^^^
  /C:/src/flutter/packages/flutter_web_plugins/lib/src/navigation/js_url_strategy.dart:49:19: Error: Method not found: 'allowInterop'.
      replaceState: allowInterop(strategy.replaceState),
                    ^^^^^^^^^^^^
  /C:/src/flutter/packages/flutter_web_plugins/lib/src/navigation/js_url_strategy.dart:50:9: Error: Method not found: 'allowInterop'.
      go: allowInterop(strategy.go),
          ^^^^^^^^^^^^
  
  /C:/src/flutter/.pub-cache/hosted/pub.dartlang.org/firebase_core_web-1.1.0/lib/src/interop/utils/utils.dart:85:12: Error: Method not found: 'allowInterop'.
      return allowInterop(dartObject);
             ^^^^^^^^^^^^
  /C:/src/flutter/.pub-cache/hosted/pub.dartlang.org/firebase_core_web-1.1.0/lib/src/interop/utils/utils.dart:120:27: Error: Method not found: 'allowInterop'.
    return PromiseJsImpl&lt;S&gt;(allowInterop((
                            ^^^^^^^^^^^^
  Failed to compile application.
  Exited (sigterm)
  </code></pre>
  <p>I was following the web installation guide found here: <a href="https://firebase.flutter.dev/docs/installation/web/" rel="nofollow noreferrer">https://firebase.flutter.dev/docs/installation/web/</a></p>