增加maybePop，使得willPopScope可用

lib/container/boost_container.dart

@@ -132,6 +132,8 @@ class BoostContainerState extends NavigatorState {
   @override
   BoostContainer get widget => super.widget as BoostContainer;
 
+  final List<Route<dynamic>> routerHistory = <Route<dynamic>>[];
+
   ContainerNavigatorObserver findContainerNavigatorObserver(
       Navigator navigator) {
     for (NavigatorObserver observer in navigator.observers) {
@@ -146,7 +148,7 @@ class BoostContainerState extends NavigatorState {
   @override
   void initState() {
     super.initState();
-    backPressedHandler = ()=>pop();
+    backPressedHandler = () => maybePop();
   }
 
   @override
@@ -160,6 +162,7 @@ class BoostContainerState extends NavigatorState {
   void dispose() {
     findContainerNavigatorObserver(widget)?.removeBoostNavigatorObserver(
         FlutterBoost.containerManager.navigatorObserver);
+    routerHistory.clear();
     super.dispose();
   }
 
@@ -169,18 +172,43 @@ class BoostContainerState extends NavigatorState {
     backPressedHandler?.call();
   }
 
+  @override
+  Future<bool> maybePop<T extends Object>([T result]) async {
+    final Route<T> route = routerHistory.last;
+    final RoutePopDisposition disposition = await route.willPop();
+    if (mounted) {
+      switch (disposition) {
+        case RoutePopDisposition.pop:
+          pop(result);
+          return true;
+          break;
+        case RoutePopDisposition.doNotPop:
+          return false;
+          break;
+        case RoutePopDisposition.bubble:
+          pop(result);
+          return true;
+          break;
+      }
+    }
+  }
+
   @override
   bool pop<T extends Object>([T result]) {
+    if (routerHistory.length > 1) {
+      routerHistory.removeLast();
+    }
+
     if (canPop()) {
       return super.pop(result);
     } else {
-      if (T is Map<String,dynamic>) {
-        FlutterBoost.singleton.close(uniqueId, result:result as Map<String,dynamic>);
-      }else{
+      if (T is Map<String, dynamic>) {
+        FlutterBoost.singleton
+            .close(uniqueId, result: result as Map<String, dynamic>);
+      } else {
         FlutterBoost.singleton.close(uniqueId);
       }
     }
-
     return false;
   }
 
@@ -194,6 +222,8 @@ class BoostContainerState extends NavigatorState {
 
     Future<T> future = super.push<T>(newRoute ?? route);
 
+    routerHistory.add(route);
+
     if (FlutterBoost.containerManager.postPushRoute != null) {
       FlutterBoost.containerManager
           .postPushRoute(name, uniqueId, params, newRoute ?? route, future);