Custom Elements: Check Definition in createElement, Create Customized Built-in Elements Sync

third_party/WebKit/LayoutTests/custom-elements/v0-v1-interop.html

Index: third_party/WebKit/LayoutTests/custom-elements/v0-v1-interop.html
diff --git a/third_party/WebKit/LayoutTests/custom-elements/v0-v1-interop.html b/third_party/WebKit/LayoutTests/custom-elements/v0-v1-interop.html
index ce7e824e634fb6db013db3815b03329b4ef1cc07..19eaf29432e990849feeeec1d99efafbed46cecd 100644
--- a/third_party/WebKit/LayoutTests/custom-elements/v0-v1-interop.html
+++ b/third_party/WebKit/LayoutTests/custom-elements/v0-v1-interop.html
@@ -22,4 +22,33 @@ test_with_window((w) => {
     w.customElements.define('old-new', Y);
   }, '"defining" (v1) a name already "registered" (v0) should throw');
 }, 'Overlapping old and new-style custom elements are not allowed');
+
+test_with_window((w) => {
+  var A = w.document.registerElement('a-a', {
+    prototype: Object.create(w.HTMLDivElement.prototype),
+    extends: 'div'
+  });
+  var a = w.document.createElement('div', 'a-a');
+
+  assert_true(a instanceof A,
+              'V0 createElement syntax works with V0 registerElement');
+  assert_throws_dom_exception(w, 'NotFoundError', () => {
+    w.document.createElement('div', {is: 'a-a'});
+  }, 'V1 createElement syntax does not work with V0 registerElement');
+
+  class B extends w.HTMLDivElement {
+    constructor() {
+      super();
+      this.addEventListener("click", () => {
+        console.log("CLICKED B!");
+      });
+    }
+  }
+  w.customElements.define('b-b', B, {extends: 'div' });
+
+  assert_true(w.document.createElement('div', {is: 'b-b'}) instanceof B,
+              'V1 createElement syntax works with V1 defined element');
+  assert_true(w.document.createElement('div', 'b-b') instanceof w.HTMLDivElement,
+              'V0 createElement syntax does not work with V1 defined element');
+}, 'V0 and V1 definition and createElement cannot be used together');
 </script>