reportPageUpdateToEngine property Null safety
Report page update to the flutter engine when the top most page changes.
The messages are used by the web engine to update the browser URL bar.
If there are multiple DBRouterDelegate in the widget tree, at most one of them can set this property to true (typically, the top-most one created from the WidgetsApp). Otherwise, the web engine may receive multiple route update messages from different navigators and fail to update the URL bar.
final bool reportPageUpdateToEngine;