Element's attribute NS API should defined undefined namespace as null instead of converting it to the "undefined" String. This is because the namespace parameter is a nullable String as per the DOM spec: https://dom.spec.whatwg.org/#element The attribute is nullable and WebIDL says undefined should be converted to null for nullable parameters: https://heycam.github.io/webidl/#es-nullable-type (step 3)
Created attachment 261338 [details] Patch
rdar://problem/22562204
Comment on attachment 261338 [details] Patch View in context: https://bugs.webkit.org/attachment.cgi?id=261338&action=review > Source/WebCore/ChangeLog:9 > + Element's attribute NS API should defined undefined namespace as null should treat?
Committed r189893: <http://trac.webkit.org/changeset/189893>