implement update action for reload button

src/browser/main/tab/page/navigation/request/mod.rs

@@ -1,4 +1,4 @@
-use gtk::Entry;
+use gtk::{prelude::EntryExt, Entry};
 
 pub struct Request {
     widget: Entry,
@@ -25,4 +25,8 @@ impl Request {
     pub fn widget(&self) -> &Entry {
         &self.widget
     }
+
+    pub fn is_empty(&self) -> bool {
+        0 == self.widget.text_length()
+    }
 }