A clonable ShadowRoot is always cloned

https://bugs.webkit.org/show_bug.cgi?id=272089

Reviewed by Ryosuke Niwa.

This aligns us with other browsers and this change to the DOM standard:
whatwg/dom#1272

* LayoutTests/imported/w3c/web-platform-tests/shadow-dom/shadow-root-clonable-expected.txt:
* Source/WebCore/dom/Element.cpp:
(WebCore::Element::cloneNodeInternal): This is the change that makes the test pass.
* Source/WebCore/dom/ShadowRoot.cpp:
(WebCore::ShadowRoot::cloneNodeInternal): This cleans up a conditional that is always true.

Canonical link: https://commits.webkit.org/277066@main

Author: annevk

LayoutTests/imported/w3c/web-platform-tests/shadow-dom/shadow-root-clonable-expected.txt

@@ -1,5 +1,5 @@
 
-FAIL attachShadow with clonable: true null is not an object (evaluating 'shallowClonedRoot.clonable')
+PASS attachShadow with clonable: true
 PASS attachShadow with clonable: false
 PASS attachShadow with clonable: undefined
 PASS declarative shadow roots do *not* get clonable: true automatically

Source/WebCore/dom/Element.cpp

@@ -579,7 +579,6 @@ Ref<Node> Element::cloneNodeInternal(Document& targetDocument, CloningOperation
 {
     switch (type) {
     case CloningOperation::OnlySelf:
-        return cloneElementWithoutChildren(targetDocument);
     case CloningOperation::SelfWithTemplateContent: {
         Ref clone = cloneElementWithoutChildren(targetDocument);
         ScriptDisallowedScope::EventAllowedScope eventAllowedScope { clone };

Source/WebCore/dom/ShadowRoot.cpp

@@ -236,10 +236,11 @@ bool ShadowRoot::childTypeAllowed(NodeType type) const
 Ref<Node> ShadowRoot::cloneNodeInternal(Document& targetDocument, CloningOperation type)
 {
     RELEASE_ASSERT(m_mode != ShadowRootMode::UserAgent);
+    ASSERT(m_isClonable);
     switch (type) {
     case CloningOperation::SelfWithTemplateContent:
         return create(targetDocument, m_mode, m_slotAssignmentMode, m_delegatesFocus ? DelegatesFocus::Yes : DelegatesFocus::No,
-            m_isClonable ? Clonable::Yes : Clonable::No, m_availableToElementInternals ? AvailableToElementInternals::Yes : AvailableToElementInternals::No);
+            Clonable::Yes, m_availableToElementInternals ? AvailableToElementInternals::Yes : AvailableToElementInternals::No);
     case CloningOperation::OnlySelf:
     case CloningOperation::Everything:
         break;