Fixing build bustage

content/html/content/src/nsHTMLAtomList.h

@@ -256,6 +256,7 @@ HTML_ATOM(selected, "selected")
 HTML_ATOM(selectedindex, "selectedindex")
 HTML_ATOM(setcookie, "set-cookie")
 HTML_ATOM(shape, "shape")
+HTML_ATOM(simple, "simple")
 HTML_ATOM(size, "size")
 HTML_ATOM(small, "small")
 HTML_ATOM(spacer, "spacer")