Fix flutter测获取屏幕宽度为0的问题

android/src/main/java/com/idlefish/flutterboost/XFlutterView.java

@@ -802,6 +802,7 @@ public class XFlutterView extends FrameLayout {
               + "FlutterView was not attached to a FlutterEngine.");
       return;
     }
+    if(viewportMetrics.width==0&&viewportMetrics.height==0)return;
 
     viewportMetrics.devicePixelRatio = getResources().getDisplayMetrics().density;
     flutterEngine.getRenderer().setViewportMetrics(viewportMetrics);