Add "Failed" custom element state

third_party/WebKit/LayoutTests/custom-elements/spec/resources/custom-elements-helpers.js

Index: third_party/WebKit/LayoutTests/custom-elements/spec/resources/custom-elements-helpers.js
diff --git a/third_party/WebKit/LayoutTests/custom-elements/spec/resources/custom-elements-helpers.js b/third_party/WebKit/LayoutTests/custom-elements/spec/resources/custom-elements-helpers.js
index c4a9e6c5ad706f69b376873bdf97bd5e735f8ef4..d5030f00c8392faac87038e21f1279360bf683ef 100644
--- a/third_party/WebKit/LayoutTests/custom-elements/spec/resources/custom-elements-helpers.js
+++ b/third_party/WebKit/LayoutTests/custom-elements/spec/resources/custom-elements-helpers.js
@@ -1,7 +1,7 @@
-function create_window_in_test(t) {
+function create_window_in_test(t, srcdoc) {
   let p = new Promise((resolve) => {
     let f = document.createElement('iframe');
-    f.srcdoc = '';
+    f.srcdoc = srcdoc ? srcdoc : '';
     f.onload = (event) => {
       let w = f.contentWindow;
       t.add_cleanup(() => f.remove());
@@ -12,9 +12,9 @@ function create_window_in_test(t) {
   return p;
 }
 
-function test_with_window(f, name) {
+function test_with_window(f, name, srcdoc) {
   promise_test((t) => {
-    return create_window_in_test(t)
+    return create_window_in_test(t, srcdoc)
     .then((w) => {
       f(w);
     });