Grr.

common/modules/buffer.jsm

@@ -877,6 +877,7 @@ var Buffer = Module("Buffer", {
     showElementInfo: function showElementInfo(elem) {
         let { dactyl } = this.modules;
 
+        XML.ignoreWhitespace = XML.prettyPrinting = false;
         dactyl.echo(<><!--L-->Element:<br/>{util.objectToString(elem, true)}</>);
     },
 

common/modules/dom.jsm

@@ -1456,7 +1456,7 @@ var DOM = Class("DOM", {
      * @returns {Node}
      */
     fromXML: function fromXML(node, doc, nodes) {
-        XML.prettyPrinting = false;
+        XML.ignoreWhitespace = XML.prettyPrinting = false;
         if (typeof node === "string") // Sandboxes can't currently pass us XML objects.
             node = XML(node);