Don't override every method in docShell, only those where webShell ne…

…eds to do different things. Remove dependency on nsIBrowserWindow. WebShell should no longer create the native widget. Removed a number of APIs from nsIWebShell to continue thining it down until it is completely removed. Other general cleanup and removal of dead code. Sizing and positioning is left nearly completely up to docShell. The bounds must be stored locally for now as there is a problem with the sizeToContent when the child has already been reflowed on an unconstrained basis, this will be fixed soon thus allowing the removal of the locally cached bounds. HandleUnknownContentType is no longer part of nsIDocumentLoaderObserver.