There are several items in walletpreview.xul that are being set programatically from the associated .js file only because no .dtd file existed but a .properties file did exist. A .dtd file should be created, all items moved from the .properties file to the .dtd file, and the values should be established statically.
Fix is included in the patch in bug 72855. Checked in.
Verified dtd checked into lxr.mozilla.org