Bug 840388 - Check if a iframe has any https parents. If not, then there is no mixed content since we are not on a secure page. r=smaug
Bug 840388 - Mochitests that navigate https frames to http frames, both when a secure parent exists and when no secure parents exist.  Tested with the mixed active content pref enabled and disabled. r=smaug
Bug 836951 - Add mDocShell to nsSecureBrowserUIImpl. Traverse up to the root doc shell. r=bsmith,smaug