method when the load type is user click to find the preferred registered window for handling the content
r=travis
git-svn-id: svn://10.0.0.236/trunk@59758 18797224-902f-48f8-a5cc-f745e15eee43
remove CanHandleConent. I don't think we need this. Also remove notion of getting a parent
content handler. This doesn't make sense anymore for how I'm defining a content handler.
Added progid prefix for content handler.
git-svn-id: svn://10.0.0.236/trunk@52880 18797224-902f-48f8-a5cc-f745e15eee43
