fix(installations, web): More explicit interop types

Author: MichaelVerdon

packages/firebase_app_installations/firebase_app_installations_web/lib/src/interop/installations_interop.dart

@@ -30,12 +30,15 @@ external JSPromise /* void */ deleteInstallations(
 @JS()
 @staticInterop
 external JSFunction onIdChange(
-    InstallationsJsImpl installations, JSFunction forceRefresh);
+    JSObject installations, JSFunction forceRefresh);
 
-@JS('Installations')
-@staticInterop
-abstract class InstallationsJsImpl {}
-
-extension InstallationsJsImplExtension on InstallationsJsImpl {
+extension type InstallationsJsImplExtension._(JSObject _) implements JSObject {
   external AppJsImpl get app;
 }
+
+extension type InstallationsJsImpl._(JSObject _) implements JSObject {
+  external JSPromise<JSString> getId();
+  external JSPromise<JSString> getToken([JSBoolean? forceRefresh]);
+  external JSPromise deleteInstallations();
+  external JSFunction onIdChange(JSFunction forceRefresh);
+}