Implement "create an element" when sync for Custom Element V1

third_party/WebKit/Source/core/dom/Document.idl

Index: third_party/WebKit/Source/core/dom/Document.idl
diff --git a/third_party/WebKit/Source/core/dom/Document.idl b/third_party/WebKit/Source/core/dom/Document.idl
index 0a3f84135dcbd9f30c6873801ba48d4b8e3b7e56..d2d6aeb7a6d02b3b201328c1e922b4919fa209ba 100644
--- a/third_party/WebKit/Source/core/dom/Document.idl
+++ b/third_party/WebKit/Source/core/dom/Document.idl
@@ -54,8 +54,8 @@ interface Document : Node {
     HTMLCollection getElementsByTagNameNS(DOMString? namespaceURI, DOMString localName);
     HTMLCollection getElementsByClassName(DOMString classNames);
 
-    [NewObject, CustomElementCallbacks, PerWorldBindings, RaisesException] Element createElement(DOMString localName);
-    [NewObject, CustomElementCallbacks, RaisesException] Element createElementNS(DOMString? namespaceURI, DOMString qualifiedName);
+    [NewObject, DoNotTestNewObject, CustomElementCallbacks, PerWorldBindings, RaisesException] Element createElement(DOMString localName);
+    [NewObject, DoNotTestNewObject, CustomElementCallbacks, RaisesException] Element createElementNS(DOMString? namespaceURI, DOMString qualifiedName);

[haraken, 2016/06/13 09:05:35]

Would you help me understand why you need [DoNotTestNewObject]?

[kojii, 2016/06/13 10:28:25]

NewObjet tests if JS wrapper hasn't been created for the native object. With
custom elements, JS constructor already runs for the element with "this" set to
the element, so the test fails.

Consulted with yukishiino, advised to add this attribute in such case. He also
recommended to add DCHECK for such methods, but in this case I couldn't find
good place to add.

     [NewObject] DocumentFragment createDocumentFragment();
     [NewObject] Text createTextNode(DOMString data);
     [NewObject] Comment createComment(DOMString data);