Ubuntu-bug does not support wine installed from winehq.org.
So where do I report the bug? It seems that wine-gecko1.5 package is installed, but when creating a new wineprefix, wine tells me that gecko is missing.
Following these commands seem to resolve the issue.
$ wget http://downloads.sourceforge.net/wine/wine_gecko-1.6-x86.msi $ sudo mkdir -p /usr/share/wine/gecko $ sudo mv wine_gecko-1.6-x86.msi /usr/share/wine/gecko/