With a debug build, the ASSERT([view isKindOfClass:[WebHTMLView class]]) in -[WebHTMLView _topHTMLView] fails when you open the URL (or any document containing a non-linking image) in Safari and drag the image into the address bar. When not using a debug build, the operation succeeds, but subsequently the web view no longer accepts URLs dragged and dropped into it.
Created attachment 8868 [details] Proposed patch
Comment on attachment 8868 [details] Proposed patch Looks OK. r=me
fixed in r14897