2nd arg of document.createElement should be an object

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 8598cce63865cf7af00397d9c0ec2330cfe9de6e..9d7a96784a9eca7e3b20c6096cd5e97ddf46e235 100644
--- a/third_party/WebKit/Source/core/dom/Document.idl
+++ b/third_party/WebKit/Source/core/dom/Document.idl
@@ -175,8 +175,8 @@ interface Document : Node {
     [CallWith=ScriptState, CustomElementCallbacks, RaisesException, MeasureAs=DocumentRegisterElement] CustomElementConstructor registerElement(DOMString type, optional ElementRegistrationOptions options);
     // http://w3c.github.io/webcomponents/spec/custom/#extensions-to-document-interface-to-instantiate
     // FIXME: The typeExtension arguments should not be nullable.
-    [CustomElementCallbacks, PerWorldBindings, RaisesException] Element createElement(DOMString localName, DOMString? typeExtension);
-    [CustomElementCallbacks, RaisesException] Element createElementNS(DOMString? namespaceURI, DOMString qualifiedName, DOMString? typeExtension);
+    [CustomElementCallbacks, PerWorldBindings, RaisesException] Element createElement(DOMString localName, (ElementCreationOptions or DOMString) options);

[Yuki, 2016/09/15 08:01:39]

Just drop-by: The spec is saying |optional ElementCreationOptions| and the old
implementaion was |DOMString?|, so should we keep supporting undefined, too?

Should be (ElementCreationOptions? or DOMString), or something like that?

[Anton Obzhirov, 2016/09/21 15:05:12]

Sorry for late reply. As for DOMString? there is a todo somewhere to make second
string argument not nullable. in Firefox it is not.
As for the optional part there is Element createElement(DOMString localName)
declaration which will be called in the case of one argument. Probably
the two createElement declarations can be merged with making the second argument
optional.

+    [CustomElementCallbacks, RaisesException] Element createElementNS(DOMString? namespaceURI, DOMString qualifiedName, (ElementCreationOptions or DOMString) options);
 
     // Page Visibility
     // http://www.w3.org/TR/page-visibility/#sec-document-interface