Browser: Open links with target="_blank" in new tab

Author: https://github.com/linusg
Commit: 896decd4d5
Pull-request: https://github.com/SerenityOS/serenity/pull/1939

Applications/Browser/Tab.h

@@ -44,6 +44,7 @@ public:
     void did_become_active();
 
     Function<void(String)> on_title_change;
+    Function<void(URL&)> on_tab_open_request;
     Function<void(Tab&)> on_tab_close_request;
 
     const String& title() const { return m_title; }