Fix side-by-side fragments by walking in reverse (#2841)

* got a repro, but no solution :(

* hmmmmm 🤔

* awyayayayayayya

* omg it's because we dont create in rev

* Make nodes rev

* fix tests compile

* Clean up PR

* revert changes to native

* Clean up PR, add test

packages/core/tests/many_roots.rs

@@ -0,0 +1,53 @@
+#![allow(non_snake_case)]
+
+use dioxus::dioxus_core::Mutation::*;
+use dioxus::prelude::*;
+use dioxus_core::ElementId;
+
+/// Should push the text node onto the stack and modify it
+#[test]
+fn many_roots() {
+    fn app() -> Element {
+        rsx! {
+            div {
+                MyNav {}
+                MyOutlet {}
+            }
+        }
+    }
+
+    fn MyNav() -> Element {
+        rsx!(
+            div { "trailing nav" }
+            div { "whhhhh"}
+            div { "bhhhh" }
+        )
+    }
+
+    fn MyOutlet() -> Element {
+        rsx!(
+            div { "homepage 1" }
+        )
+    }
+
+    let mut dom = VirtualDom::new(app);
+    let edits = dom.rebuild_to_vec();
+
+    assert_eq!(
+        edits.edits,
+        [
+            // load the div {} container
+            LoadTemplate { index: 0, id: ElementId(1) },
+            // Load myoutlet first
+            LoadTemplate { index: 0, id: ElementId(2) },
+            ReplacePlaceholder { path: &[1], m: 1 },
+            // Then the MyNav
+            LoadTemplate { index: 0, id: ElementId(3) },
+            LoadTemplate { index: 1, id: ElementId(4) },
+            LoadTemplate { index: 2, id: ElementId(5) },
+            ReplacePlaceholder { path: &[0], m: 3 },
+            // Then mount the div to the dom
+            AppendChildren { m: 1, id: ElementId(0) },
+        ]
+    )
+}