Bug 860951 - Make newlines work in XUL alerts. r=Unfocused

--HG--
extra : rebase_source : a18b39cad30e711e033c91a2e67979884a8c68cf

toolkit/components/alerts/resources/content/alert.css

@@ -8,6 +8,10 @@
   animation-name: alert-animation;
 }
 
+.alertText {
+    white-space: pre-wrap;
+}
+
 @keyframes alert-animation {
   to {
     visibility: hidden;