Comment 7 for bug 186726

but it is a dependency of flashplugin-nonfree. (check it yourself)

however, there is a problem for people who installed flash player a kludgy way (in an older install) and now have the plugin for flash in ~/.mozilla/plugins, so have flash without the actual package flashplugin-nonfree installed. for these people libflashsupprt wont be installed, and they could be left with problems.

era, was this what happened to you too? can you confirm this is a problem in this set up?
maybe firefox should depend on libflashsupport, just in case
or maybe old flash plugins should be deleted, from ~/.mozilla/plugins, which would then prompt the user to reinstall flash on first visit to flash site, where install would be done through apt, and then be safe from this problem in the future.

this is a bug, but only for non standard people (perhaps people who have used automatix or something similar previously?)