Push-pop custom elements reaction stack when the parser inserts elements

third_party/WebKit/LayoutTests/custom-elements/spec/parsing.html

Index: third_party/WebKit/LayoutTests/custom-elements/spec/parsing.html
diff --git a/third_party/WebKit/LayoutTests/custom-elements/spec/parsing.html b/third_party/WebKit/LayoutTests/custom-elements/spec/parsing.html
index 9826f8aab3b5bbf7f5161c8fb2d3a0c3f5c18f83..9b5b1ddec34e801d8833681138e6f961d8ca8997 100644
--- a/third_party/WebKit/LayoutTests/custom-elements/spec/parsing.html
+++ b/third_party/WebKit/LayoutTests/custom-elements/spec/parsing.html
@@ -68,6 +68,31 @@ test_with_content((w) => {
 });
 </script>
 
+<template data-test="foreign content insertion executes connected">
+  <script>
+  'use strict';
+
+  customElements.define('a-a', class extends HTMLElement {
+    constructor() {
+      super();
+    }
+    connectedCallback() {
+      window.connectedChildNodeCount = this.childNodes.length;
+    }
+  });
+  </script>
+  <a-a><div></div></a-a>
+</template>
+<script>
+'use strict';
+
+test_with_content((w) => {
+  assert_equals(w.connectedChildNodeCount, 0,
+      'the parser should have run the connected callback when inserting the ' +
+      'element, before continuing tree construction');
+});
+</script>
+
 <template data-test="element creation failure produces unknown element">
   <script>
   'use strict';