[scoped-registry] Null registry element should get registry on adopt

instead of insert

It was discussed over TPAC and outlined in
whatwg/dom#1423 that we want to set registry on
null registry element during adoption instead of insertion of a node.

Bug: 448853877
Change-Id: I63b8a7bcef98ead66bd1375c9b1df69d9b9bd597

Author: Jayson Chen

custom-elements/registries/element-mutation.html

@@ -31,49 +31,55 @@
 
 <script>
 
-test(() => {
-    const registry = new CustomElementRegistry;
+function runTests(mutation, mutationName) {
+    test(() => {
+        const registry = new CustomElementRegistry;
 
-    const element = document.createElement('new-element');
-    assert_equals(element.customElementRegistry, window.customElements);
+        const element = document.createElement('new-element');
+        assert_equals(element.customElementRegistry, window.customElements);
 
-    document.body.appendChild(element);
-    const shadow = document.createElement('div').attachShadow({mode: 'open', customElementRegistry: registry})
-    shadow.appendChild(element)
-    assert_not_equals(element.customElementRegistry, registry);
+        mutation(document.body, element);
+        const shadow = document.createElement('div').attachShadow({mode: 'open', customElementRegistry: registry})
+        mutation(shadow, element);
+        assert_not_equals(element.customElementRegistry, registry);
 
-    document.body.appendChild(element)
-    assert_equals(element.customElementRegistry, window.customElements);
-}, "An element with global registry should not change its registry when moved into a shadow tree with scoped registry.")
+        mutation(document.body, element);
+        assert_equals(element.customElementRegistry, window.customElements);
+    }, "An element with global registry should not change its registry when run " + mutationName + " into a shadow tree with scoped registry.")
 
-test(() => {
-    const clone = host.cloneNode(true);
-    const shadowRoot1 = clone.querySelector('#shadow-host-1').shadowRoot;
-    const element = shadowRoot1.querySelector('#shadow-host-1-child');
+    test(() => {
+        const clone = host.cloneNode(true);
+        const shadowRoot1 = clone.querySelector('#shadow-host-1').shadowRoot;
+        const element = shadowRoot1.querySelector('#shadow-host-1-child');
 
-    const registry1 = new CustomElementRegistry;
-    registry1.initialize(shadowRoot1);
-    assert_equals(element.customElementRegistry, registry1);
+        const registry1 = new CustomElementRegistry;
+        registry1.initialize(shadowRoot1);
+        assert_equals(element.customElementRegistry, registry1);
 
-    document.querySelector('#host').appendChild(element);
-    assert_equals(element.customElementRegistry, registry1);
-}, "An element with scoped registry should not change its registry when moved out of the shadow tree.")
+        mutation(document.querySelector('#host'), element);
+        assert_equals(element.customElementRegistry, registry1);
+    }, "An element with scoped registry should not change its registry when run " + mutationName + " out of the shadow tree.")
 
-test(() => {
-    const clone = host.cloneNode(true);
-    const shadowRoot1 = clone.querySelector('#shadow-host-1').shadowRoot;
-    const shadowRoot2 = clone.querySelector('#shadow-host-2').shadowRoot;
-    const element = shadowRoot1.querySelector('#shadow-host-1-child');
-
-    const registry1 = new CustomElementRegistry;
-    const registry2 = new CustomElementRegistry;
-    registry1.initialize(shadowRoot1);
-    registry2.initialize(shadowRoot2);
-    assert_equals(element.customElementRegistry, registry1);
-
-    shadowRoot2.appendChild(element);
-    assert_equals(element.customElementRegistry, registry1);
-}, "An element with scoped registry should not change its registry when moved into another shadow tree with different scoped registry.")
+    test(() => {
+        const clone = host.cloneNode(true);
+        const shadowRoot1 = clone.querySelector('#shadow-host-1').shadowRoot;
+        const shadowRoot2 = clone.querySelector('#shadow-host-2').shadowRoot;
+        const element = shadowRoot1.querySelector('#shadow-host-1-child');
+
+        const registry1 = new CustomElementRegistry;
+        const registry2 = new CustomElementRegistry;
+        registry1.initialize(shadowRoot1);
+        registry2.initialize(shadowRoot2);
+        assert_equals(element.customElementRegistry, registry1);
+
+        mutation(shadowRoot2, element);
+        assert_equals(element.customElementRegistry, registry1);
+    }, "An element with scoped registry should not change its registry when run " + mutationName + " into another shadow tree with different scoped registry.")
+};
+
+runTests(function (parent, child) { parent.append(child); }, "append");
+runTests(function (parent, child) { parent.appendChild(child); }, "appendChild");
+runTests(function (parent, child) { parent.prepend(child); }, "prepend");
 
 test(() => {
     customElements.define('x-foo', class extends HTMLElement {});