more 65251, package strings in appropriate jar file. patch from jag, r=hixie sr=ben

extensions/content-packs/resources/jar.mn

@@ -2,6 +2,8 @@ content-packs.jar:
       content/content-packs/contents.rdf                (content/contents.rdf)
       content/content-packs/prefOverlay.xul             (content/prefOverlay.xul)
       content/content-packs/pref-contentpacks.xul       (content/pref-contentpacks.xul)
+
+en-US.jar:
       locale/en-US/content-packs/prefOverlay.dtd        (locale/en-US/prefOverlay.dtd)
       locale/en-US/content-packs/pref-contentpacks.dtd  (locale/en-US/pref-contentpacks.dtd)
       locale/en-US/content-packs/contents.rdf           (locale/en-US/contents.rdf)