The test plugins/destroy-during-npp-new.html is failing because the window is not even created. Its window.open('data:text/html,Hello world!') returns undefined. A window.open('http://webkit.org/') also doesn't work when run from inside a page. Both work when run from the inspector.
Created attachment 39995 [details]
small test case
We seem to pass this now, I've unskipped it in r55356.