Make custom elements work in HTML imports

third_party/WebKit/LayoutTests/custom-elements/imports/resources/inner-html.html

Index: third_party/WebKit/LayoutTests/custom-elements/imports/resources/inner-html.html
diff --git a/third_party/WebKit/LayoutTests/custom-elements/imports/resources/inner-html.html b/third_party/WebKit/LayoutTests/custom-elements/imports/resources/inner-html.html
new file mode 100644
index 0000000000000000000000000000000000000000..705f590fe2d952db4a2d8ceca28a0525a1243855
--- /dev/null
+++ b/third_party/WebKit/LayoutTests/custom-elements/imports/resources/inner-html.html
@@ -0,0 +1,26 @@
+<div id="sandbox"></div>
+<script>
+'use strict';
+
+let constructors = [];
+
+test(() => {
+  assert_equals(constructors.length, 0);
+
+  customElements.define('a-a', class extends HTMLElement {
+    constructor() {
+      super();
+      constructors.push(this);
+    }
+  });
+
+  let importDoc = document.currentScript.ownerDocument;
+  let sandbox = importDoc.querySelector('#sandbox');
+
+  // createElement should synchronously customize.
+  sandbox.innerHTML = '<a-a id="x"></a-a>';
+
+  assert_equals(constructors.length, 1);
+  assert_equals(constructors[0].id, 'x');
+}, 'innerHTML with Custom Elements should work in imported document.');
+</script>