Fix hydration with empty spread attributes (#4647)

* Fix hydration of empty spread attributes

* add a regression test

* fix doctest

packages/playwright-tests/fullstack-spread/src/main.rs

@@ -0,0 +1,40 @@
+//! Regression test for <https://github.com/DioxusLabs/dioxus/issues/4646>
+
+use dioxus::prelude::*;
+
+fn main() {
+    dioxus::launch(|| {
+        rsx! {
+            Comp {}
+            Comp {}
+            Button {}
+        }
+    });
+}
+
+#[component]
+fn Button() -> Element {
+    let mut count = use_signal(|| 0);
+
+    rsx! {
+        button {
+            id: "counter",
+            onclick: move |_| {
+                count += 1;
+            },
+            "Count: {count}"
+        }
+    }
+}
+
+#[component]
+fn Comp(#[props(extends = GlobalAttributes)] attributes: Vec<Attribute>) -> Element {
+    rsx! {
+        div {
+            width: 100,
+            div {
+                ..attributes,
+            }
+        }
+    }
+}