Fix incorrect `'navigator'` check (#32219)

app/javascript/mastodon/actions/markers.ts

@@ -37,8 +37,7 @@ export const synchronouslySubmitMarkers = createAppAsyncThunk(
       });
 
       return;
-      // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
+    } else if ('sendBeacon' in navigator) {
-    } else if ('navigator' && 'sendBeacon' in navigator) {
       // Failing that, we can use sendBeacon, but we have to encode the data as
       // FormData for DoorKeeper to recognize the token.
       const formData = new FormData();