TF-2533 reset _htmlData value when screen dispose

core/lib/presentation/views/html_viewer/html_content_viewer_on_web_widget.dart

@@ -305,4 +305,10 @@ class _HtmlContentViewerOnWebState extends State<HtmlContentViewerOnWeb> {
 
     html.window.postMessage(jsonGetWidth, '*');
   }
+
+  @override
+  void dispose() {
+    _htmlData = null;
+    super.dispose();
+  }
 }

core/lib/presentation/views/html_viewer/html_content_viewer_widget.dart

@@ -277,6 +277,7 @@ class _HtmlContentViewState extends State<HtmlContentViewer> {
   @override
   void dispose() {
     _loadingBarNotifier.dispose();
+    _htmlData = null;
     super.dispose();
   }
 }