LibWeb: Remove document_setter from Window.document

It is readonly: https://html.spec.whatwg.org/multipage/window-object.html#the-window-object:dom-document-2

Userland/Libraries/LibWeb/Bindings/WindowObject.cpp

@@ -66,7 +66,7 @@ void WindowObject::initialize_global_object()
     define_property("window", this, JS::Attribute::Enumerable);
     define_property("frames", this, JS::Attribute::Enumerable);
     define_property("self", this, JS::Attribute::Enumerable);
-    define_native_property("document", document_getter, document_setter, JS::Attribute::Enumerable);
+    define_native_property("document", document_getter, nullptr, JS::Attribute::Enumerable);
     define_native_property("performance", performance_getter, nullptr, JS::Attribute::Enumerable);
     define_native_property("screen", screen_getter, nullptr, JS::Attribute::Enumerable);
     define_native_property("innerWidth", inner_width_getter, nullptr, JS::Attribute::Enumerable);
@@ -360,11 +360,6 @@ JS_DEFINE_NATIVE_GETTER(WindowObject::document_getter)
     return wrap(global_object, impl->document());
 }
 
-JS_DEFINE_NATIVE_SETTER(WindowObject::document_setter)
-{
-    // FIXME: Figure out what we should do here. Just ignore attempts to set window.document for now.
-}
-
 JS_DEFINE_NATIVE_GETTER(WindowObject::performance_getter)
 {
     auto* impl = impl_from(vm, global_object);

Userland/Libraries/LibWeb/Bindings/WindowObject.h

@@ -79,7 +79,6 @@ private:
     virtual void visit_edges(Visitor&) override;
 
     JS_DECLARE_NATIVE_GETTER(document_getter);
-    JS_DECLARE_NATIVE_SETTER(document_setter);
 
     JS_DECLARE_NATIVE_GETTER(performance_getter);
     JS_DECLARE_NATIVE_GETTER(screen_getter);