[Ur] Several patches and questions

[Edward Z. Yang]

Excerpts from Adam Chlipala's message of Mon Dec 31 22:06:47 +0800 2012:
> By the way, allowing unrestricted use of the <meta> tag is poking a big 
> hole in the nice guarantees that Ur/Web gives, so I'd think twice before 
> exposing such with the FFI. ;)

Yeah, that's not surprising.  Too bad I can't name the tag 'unsafeMeta' ;-)
(In this case, I need it because an external JS lib is looking for the
tag and won't fire if it's not present.)

Edward