borisyankov/DefinitelyTyped — pull request #1909 by jvilk (2014-03-24 16:29:13+00:00)
Title: [filesystem] FileSystem `root` is a DirectoryEntry.

This is specified in the official standard:
http://www.w3.org/TR/file-system-api/#the-filesystem-interface

Interestingly enough, these typings already specify the `root` of FileSystemSync (the synchronous version of the API) to be a DirectorySync. This must have been an oversight of the original author of these typings.