I don't know the ins and outs of HTML5 DnD, but this doesn't have any glaring errors.
Make the screenshot drag-and-drop support require a modern HTML5 browser..
Review Request #1367 — Created Jan. 28, 2010 and submitted
Make the screenshot drag-and-drop support require a modern HTML5 browser.. The screenshot drag-and-drop support required Google Gears before, but the remote file upload and drag-and-drop support was broken since Firefox 3.5 came out, and never fixed. We now use the new APIs in modern HTML5 browsers. This works in Firefox 3.6 and should work in newer Google Chrome/Safari browsers, but haven't been tested.
Tested uploading with Firefox 3.6.