Fix implementation of #78

Brain fart when writing and testing the first attempt.
I can only actually reproduce the underlying issue in the REPL so I haven't confirmed that this fixes it.

src/lib/components/portal/Portal.svelte

@@ -2,6 +2,7 @@
   import { usePortalGroupContext } from "./PortalGroup.svelte";
   import { usePortalRoot } from "$lib/internal/ForcePortalRootContext.svelte";
   import { portal } from "$lib/hooks/use-portal";
+  import { tick } from "svelte";
   let forceInRoot = usePortalRoot();
   let groupTarget = usePortalGroupContext();
   $: target = (() => {
@@ -20,6 +21,15 @@
 
     let root = document.createElement("div");
     root.setAttribute("id", "headlessui-portal-root");
+    // During initial render, the "portal" might be constructed before
+    // the root component has even attached, causing the portal to not work.
+    // This is a workaround for this issue--it can't guarantee the portal is
+    // **always** last, but it should catch the normal cases.
+    tick().then(() => {
+      if (root !== document.body.lastChild) {
+        document.body.appendChild(root);
+      }
+    });
     return document.body.appendChild(root);
   })();
 </script>

src/lib/components/portal/portal.test.ts

@@ -334,26 +334,3 @@ it('should cleanup the Portal properly when Svelte would not detach it', async (
   expect(getPortalRoot()).not.toBe(null)
   expect(getPortalRoot().childNodes).toHaveLength(1)
 })
-
-it('should move the Portal last during initial render', async () => {
-  expect(getPortalRoot()).toBe(null)
-
-  // We need to use a custom target because of the implementation of
-  // render() in the testing library
-  render(svelte`
-    <script>
-      let target = document.body.firstChild;
-    </script>
-
-    <PortalGroup {target}>
-      <Portal>Portal</Portal>
-    </PortalGroup>
-    <main>Main</main>
-    `)
-
-  await tick();
-
-  expect(document.body.innerHTML).toMatchInlineSnapshot(
-    `"<div> <main>Main</main><div>Portal</div></div>"`
-  )
-})

src/lib/hooks/use-portal.ts

@@ -1,20 +1,9 @@
-import { tick } from "svelte";
-
 export function portal(
   element: HTMLElement,
   target: HTMLElement | null | undefined
 ) {
   if (target) {
     target.append(element);
-    // During initial render, the "portal" might be constructed before
-    // the root component has even attached, causing the portal to not work.
-    // This is a workaround for this issue--it can't guarantee the portal is
-    // **always** last, but it should catch the normal cases.
-    tick().then(() => {
-      if (target && element !== target.lastChild) {
-        target.appendChild(element);
-      }
-    });
   }
   return {
     update(newTarget: HTMLElement) {