Remove "mini-DSR" and replace with declarative Shadow DOM

Change-Id: Idf58c176a453d6fc64b35fe284ac7a1cd2145dfd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2485697
Commit-Queue: Kouhei Ueno <kouhei@chromium.org>
Auto-Submit: Mason Freed <masonfreed@chromium.org>
Reviewed-by: Kouhei Ueno <kouhei@chromium.org>
Cr-Commit-Position: refs/heads/master@{#818829}

third_party/blink/renderer/core/dom/slot_assignment_test.cc

@@ -23,16 +23,6 @@ namespace blink {
 
 namespace {
 
-// Copy elements in HTMLCollection into a vector because HTMLCollection is a
-// live list and would be invalid if a mutation occurs.
-HeapVector<Member<Element>> CollectFromHTMLCollection(
-    HTMLCollection& collection) {
-  HeapVector<Member<Element>> elements;
-  for (Element* element : collection)
-    elements.push_back(element);
-  return elements;
-}
-
 template <class T>
 HeapVector<Member<Node>> CollectFromIterable(T iterable) {
   HeapVector<Member<Node>> nodes;
@@ -41,31 +31,6 @@ HeapVector<Member<Node>> CollectFromIterable(T iterable) {
   return nodes;
 }
 
-// Process Mini-DSL for Declarative Shadow DOM.
-
-// In Mini-DSL, <shadowroot> elements would behaves as if it were "Declarative
-// Shadow DOM". This is usuful for constructing a composed tree in testing.
-// Declarative Shadow DOM is under the dicussion. See
-// https://github.com/whatwg/dom/issues/510. Once Declarative Shadow DOM is
-// standardized and implemented, this DSL is no longer required.
-void ConvertDeclarativeShadowDOMToShadowRoot(Element& element) {
-  HTMLCollection* shadow_root_collection =
-      element.getElementsByTagName("shadowroot");
-  if (!shadow_root_collection)
-    return;
-  for (Element* shadow_root :
-       CollectFromHTMLCollection(*shadow_root_collection)) {
-    Element* parent = shadow_root->parentElement();
-    DCHECK(parent);
-    parent->removeChild(shadow_root);
-    ShadowRoot& attached_shadow_root =
-        parent->AttachShadowRootInternal(ShadowRootType::kOpen);
-    for (Node* child :
-         CollectFromIterable(NodeTraversal::ChildrenOf(*shadow_root)))
-      attached_shadow_root.AppendChild(child);
-  }
-}
-
 void RemoveWhiteSpaceOnlyTextNode(ContainerNode& container) {
   for (Node* descendant :
        CollectFromIterable(NodeTraversal::InclusiveDescendantsOf(container))) {
@@ -105,14 +70,13 @@ void SlotAssignmentTest::SetUp() {
 void SlotAssignmentTest::SetBody(const char* html) {
   Element* body = GetDocument().body();
   body->setInnerHTML(String::FromUTF8(html));
-  ConvertDeclarativeShadowDOMToShadowRoot(*body);
   RemoveWhiteSpaceOnlyTextNode(*body);
 }
 
 TEST_F(SlotAssignmentTest, DeclarativeShadowDOM) {
   SetBody(R"HTML(
     <div id=host>
-      <shadowroot></shadowroot>
+      <template shadowroot=open></template>
     </div>
   )HTML");
 
@@ -124,11 +88,11 @@ TEST_F(SlotAssignmentTest, DeclarativeShadowDOM) {
 TEST_F(SlotAssignmentTest, NestedDeclarativeShadowDOM) {
   SetBody(R"HTML(
     <div id=host1>
-      <shadowroot>
+      <template shadowroot=open>
         <div id=host2>
-          <shadowroot></shadowroot>
+          <template shadowroot=open></template>
         </div>
-      </shadowroot>
+      </template>
     </div>
   )HTML");
 
@@ -146,9 +110,9 @@ TEST_F(SlotAssignmentTest, NestedDeclarativeShadowDOM) {
 TEST_F(SlotAssignmentTest, AssignedNodesAreSet) {
   SetBody(R"HTML(
     <div id=host>
-      <shadowroot>
+      <template shadowroot=open>
         <slot></slot>
-      </shadowroot>
+      </template>
       <div id='host-child'></div>
     </div>
   )HTML");