Following up from my comment on bug #30266.
On Windows, event.dataTransfer.types is NULL on a successful drop despite any formats set in the dragstart event.
According to section 7.9.2 of the HTML 5 spec (http://dev.w3.org/html5/spec/Overview.html#the-dragevent-and-datatransfer-interfaces), it should be the list of the formats that were set in the dragstart event.
Created attachment 41438 [details]
Actually it seems to work if the registered content type is text/plain, but seems to fail for other basic ones (text/html) for example.
*** Bug 33738 has been marked as a duplicate of this bug. ***
Created attachment 46826 [details]
Comment on attachment 46826 [details]
There are a couple of conflict markers in your ChangeLogs. I'll take care of them before landing. Thanks!
Committed r53410: <http://trac.webkit.org/changeset/53410>