nsIChromeRegistry in Firefox 3.5

 refresh the chrome list at runtime, looking for new packages/etc

 Resolve a chrome URL to an loadable URI using the information in the
 registry. Does not modify aChromeURL.

 Chrome URLs are allowed to be specified in "shorthand", leaving the
 "file" portion off. In that case, the URL is expanded to:

   chrome://package/provider/package.ext

 where "ext" is:

   "xul" for a "content" package,
   "css" for a "skin" package, and
   "dtd" for a "locale" package.

 @param aChromeURL the URL that is to be converted.

 returns whether XPCNativeWrappers are enabled for aURI.