Remove intrinsic min-width of fieldset

[vanthome]

At least Firefox [1] and Chrome [2] have a legacy/ intrinsic min-width
for the fieldset element.
This removes it. The fix is especially useful on mobile.

[1] https://bugzilla.mozilla.org/show_bug.cgi?id=504622
[2] http://stackoverflow.com/questions/8084343/google-chrome-fieldset-overflow-bug

[necolas]

Properties should be in alphabetical order

[necolas]

Please squash into a single commit. You can force-push to your remote branch rather than creating another pull request.

[vanthome]

Like this?

[necolas]

Yep, thanks! Needs a test in the test.html file too please.

[vanthome]

I've added a small test although the existing fieldsets would have been enough to demonstrate the problem.

[necolas]

This doesn't seem to fix Firefox. Will probably revert this.

[vanthome]

Ok, you confirmed what I found out in my last test, I was sure that it fixes also FF but at least with 26 it isnt.
If you look at the referenced bugreport of FF, it's not yet fixed although its from 2010. Someone says that adding display:table-column; would help. Shall we try this?

[necolas]

None of the table displays works without side-effects. Doesn't seem to be much we can do to work around.