createElement should not transmit exceptions but report them.

third_party/WebKit/LayoutTests/custom-elements/spec/create-element-defined-synchronous.html

Index: third_party/WebKit/LayoutTests/custom-elements/spec/create-element-defined-synchronous.html
diff --git a/third_party/WebKit/LayoutTests/custom-elements/spec/create-element-defined-synchronous.html b/third_party/WebKit/LayoutTests/custom-elements/spec/create-element-defined-synchronous.html
index 8d4b9528773d4de0e1da63489373b9d60e5e40e0..49de1f0ee4bad82f16081e5e96e2e0d968eb75fc 100644
--- a/third_party/WebKit/LayoutTests/custom-elements/spec/create-element-defined-synchronous.html
+++ b/third_party/WebKit/LayoutTests/custom-elements/spec/create-element-defined-synchronous.html
@@ -7,14 +7,6 @@
 <script>
 'use strict';
 
-function assert_rethrown(func, description) {
-  assert_throws({ name: 'rethrown' }, () => {
-    const err = new Error('check this is rethrown');
-    err.name = 'rethrown';
-    func(err);
-  }, description);
-}
-
 const expectTypeError = TypeError.prototype;
 const expectNotSupportedError = 'NOT_SUPPORTED_ERR';
 
@@ -46,15 +38,17 @@ function test_create_element_synchronous(description, define_and_create_element)
   }, `${description}Pre-flight check should succeed`);
 
   test_with_window((w) => {
-    assert_rethrown(err => {
+    const err = new Error('check this is reported');
+    err.name = 'reported';
+    assert_reports(w, err, () => {
       define_and_create_element(w, class extends w.HTMLElement {
         constructor() { super(); throw err; }
       });
     });
-  }, `${description}6.1.2. Errors in Construct(C) should be rethrown`);
+  }, `${description}6.1.2. Errors in Construct(C) should be reported`);
 
   test_with_window((w) => {
-    assert_throws(expectTypeError, () => {
+    assert_reports(w, expectTypeError, () => {
       define_and_create_element(w, class {
         constructor() {}
       });
@@ -62,7 +56,7 @@ function test_create_element_synchronous(description, define_and_create_element)
   }, `${description}6.1.3. If result does not implement the HTMLElement interface, throw a TypeError`);
 
   test_with_window((w) => {
-    assert_throws(expectNotSupportedError, () => {
+    assert_reports(w, expectNotSupportedError, () => {
       define_and_create_element(w, class extends w.HTMLElement {
         constructor() { super(); this.setAttribute('a', 'a'); }
       });
@@ -70,20 +64,23 @@ function test_create_element_synchronous(description, define_and_create_element)
   }, `${description}6.1.4. If result\'s attribute list is not empty, then throw a NotSupportedError`);
 
   test_with_window((w) => {
-    assert_throws(expectNotSupportedError, () => {
+    assert_reports(w, expectNotSupportedError, () => {
       define_and_create_element(w, class extends w.HTMLElement {
         constructor() { super(); this.appendChild(w.document.createElement('a')); }
       });
     }, 'should throw if it has a child element');
-    assert_throws(expectNotSupportedError, () => {
+  }, `${description}6.1.5. If result has children, then throw a NotSupportedError`);
+
+  test_with_window((w) => {
+    assert_reports(w, expectNotSupportedError, () => {
       define_and_create_element(w, class extends w.HTMLElement {
-        constructor() { super(); this.appendChild(w.document.createTextNode('a')); }
+        constructor() { super(); this.append('a'); }
       });
     }, 'should throw if it has a child text node');
   }, `${description}6.1.5. If result has children, then throw a NotSupportedError`);
 
   test_with_window((w) => {
-    assert_throws(expectNotSupportedError, () => {
+    assert_reports(w, expectNotSupportedError, () => {
       define_and_create_element(w, class extends w.HTMLElement {
         constructor() { super(); w.document.createElement('div').appendChild(this); }
       });
@@ -91,25 +88,25 @@ function test_create_element_synchronous(description, define_and_create_element)
   }, `${description}6.1.6. If result\'s parent is not null, then throw a NotSupportedError`);
 
   test_with_window((w) => {
-    assert_throws(expectNotSupportedError, () => {
+    assert_reports(w, expectNotSupportedError, () => {
       define_and_create_element(w, class extends w.HTMLElement {
         constructor() { super(); return w.document.implementation.createHTMLDocument().createElement('div'); }
       });
     });
   }, `${description}6.1.7. If result\'s node document is not document, then throw a NotSupportedError`);
 
-  /* This is not testsable today, see https://github.com/whatwg/html/issues/1402
+  // See the note in step 6.1.8. In future, it may be possible to throw
+  // NotSupportedError for some elements.
   test_with_window((w) => {
-    assert_throws(expectNotSupportedError, () => {
+    assert_reports(w, expectTypeError, () => {
       define_and_create_element(w, class extends w.HTMLElement {
         constructor() { super(); return w.document.createElementNS('http://www.w3.org/2000/svg', 'g'); }
       });
     });
-  }, `${description}6.1.8. If result\'s namespace is not the HTML namespace, then throw a NotSupportedError`);
-  */
+  }, `${description}6.1.8. If result\'s namespace is not the HTML namespace, then throw (a NotSupportedError, currently TypeError)`);
 
   test_with_window((w) => {
-    assert_throws(expectNotSupportedError, () => {
+    assert_reports(w, expectNotSupportedError, () => {
       define_and_create_element(w, class extends w.HTMLElement {
         constructor() { super(); return document.createElement('div'); }
       });