Bug 853415 - Shuffle before/after around and set an ordinal value on :after to avoid overflow bug, r=MattN

--HG--
extra : rebase_source : 35ee222868c5ed8af0886d67d8dfc6c04514139a

browser/themes/osx/browser.css

@@ -2243,6 +2243,12 @@ toolbarbutton.chevron > .toolbarbutton-menu-dropmarker {
  */
 #TabsToolbar::after {
   content: '';
+  /* Because we use placeholders for window controls etc. in the tabstrip,
+   * and position those with ordinal attributes, and because our layout code
+   * expects :before/:after nodes to come first/last in the frame list,
+   * we have to reorder this element to come last, hence the
+   * ordinal group value (see bug 853415). */
+  -moz-box-ordinal-group: 1001;
   position: absolute;
   bottom: 1px;
   left: 0;

browser/themes/shared/tabs.inc.css

@@ -10,6 +10,8 @@
 
 /* image preloading hack */
 #TabsToolbar::before {
+  /* Because of bug 853415, we need to ordinal this to the first position: */
+  -moz-box-ordinal-group: 0;
   content: '';
   display: block;
   background-image: