`x-complement-fontset-spec' assuming `x-charset-registry' property

[Eric Marsden]

When w3 is loaded, calling `create-fontset-from-fontset-spec' fails
with "Wrong type argument: stringp, nil".

This is because w3 creates a charset named `w3-dingbats' but does not
associate it with a `x-charset-registry' property. The function
`x-complement-fontset-spec' (incorrectly I believe) assumes that all
fontsets will have such a property defined; this is indeed the case
for all the predefined charsets, thanks to code in fontset.el.

If this is appropriate behaviour, the docstring for `define-charset'
should be augmented to specify that a call to `put-charset-property'
is necessary for newly defined charsets. 

[This is Emacs 20.6 and WWW 4.0pre.46]

-- 
Eric Marsden                          <URL:http://www.laas.fr/~emarsden>