Bug 1876932 [wpt PR 44247] - Make shallow clone work when clonable is true, a=testonly

Automatic update from web-platform-tests
Make shallow clone work when clonable is true

This did not previously work correctly, but now, this will
work:

const shadow = host.attachShadow({mode:'open', clonable:true});
host.cloneNode(false);

The behavior is for the shadow root to be deep-cloned, even though
the `deep` argument to `cloneNode()` is `false`.

See this discussion for more context:
  whatwg/dom#1249

and this summary of the consensus:
  whatwg/dom#1249 (comment)

Bug: 1510466
Change-Id: I8a9de78044785675cd6bbac93d9b26286445ac8d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5242239
Reviewed-by: David Baron <[email protected]>
Auto-Submit: Mason Freed <[email protected]>
Commit-Queue: Mason Freed <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1254312}

--

wpt-commits: bf7b1d88809248c70531b45d7c202a1fc7993d2d
wpt-pr: 44247

Author: mfreed7

testing/web-platform/tests/shadow-dom/shadow-root-clonable.html

@@ -3,6 +3,7 @@
 <link rel='author' href='mailto:krosylight@mozilla.com'>
 <link rel='author' href='mailto:masonf@chromium.org'>
 <link rel='help' href='https://dom.spec.whatwg.org/#shadowroot-clonable'>
+<link rel='help' href='https://github.com/whatwg/dom/issues/1249#issuecomment-1917772229'>
 <script src='/resources/testharness.js'></script>
 <script src='/resources/testharnessreport.js'></script>
 
@@ -11,14 +12,22 @@
 test(() => {
   const div = document.createElement("div");
   const root = div.attachShadow({ mode: "open", clonable: true });
-  root.appendChild(document.createElement("input"));
+  root.innerHTML = '<input><div><span></span></div>';
   assert_true(root.clonable, "clonable attribute");
 
   const clone = div.cloneNode(true);
   const clonedRoot = clone.shadowRoot;
   assert_true(clonedRoot.clonable, "clone gets the same clonable state");
-  assert_equals(clonedRoot.children.length, 1, "children count");
+  assert_equals(clonedRoot.children.length, 2, "children count");
   assert_equals(clonedRoot.children[0].localName, "input", "children content");
+  assert_equals(clonedRoot.children[1].firstElementChild.localName, "span", "grandchildren content");
+
+  const shallowClone = div.cloneNode(false);
+  const shallowClonedRoot = shallowClone.shadowRoot;
+  assert_true(shallowClonedRoot.clonable, "clone gets the same clonable state");
+  assert_equals(shallowClonedRoot.children.length, 2, "shallow clone still deep-clones the shadow root");
+  assert_equals(shallowClonedRoot.children[0].localName, "input", "shadow children content");
+  assert_equals(shallowClonedRoot.children[1].firstElementChild.localName, "span", "shadow grandchildren content");
 }, "attachShadow with clonable: true");
 
 for (const clonable of [false, undefined]) {