LibWeb/HTML: Port Window.document to IDL

Author: https://github.com/linusg
Commit: 0e587420a8
Pull-request: https://github.com/SerenityOS/serenity/pull/17752
Reviewed-by: https://github.com/awesomekling

Userland/Libraries/LibWeb/HTML/Window.h

@@ -142,6 +142,7 @@ public:
     // JS API functions
     JS::NonnullGCPtr<WindowProxy> window() const;
     JS::NonnullGCPtr<WindowProxy> self() const;
+    JS::NonnullGCPtr<DOM::Document const> document() const;
 
     JS::NonnullGCPtr<WindowProxy> frames() const;
 
@@ -221,8 +222,6 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(length_getter);
     JS_DECLARE_NATIVE_FUNCTION(top_getter);
 
-    JS_DECLARE_NATIVE_FUNCTION(document_getter);
-
     JS_DECLARE_NATIVE_FUNCTION(frame_element_getter);
 
     JS_DECLARE_NATIVE_FUNCTION(location_getter);