Fix sidebar contents disappearing on show and hide.

b = 116094; r = morse; sr = alecf

suite/common/sidebar/sidebarOverlay.js

@@ -973,10 +973,12 @@ function SidebarShowHide() {
   if (sidebar_is_hidden()) {
     debug("Showing the sidebar");
     sidebar_box.removeAttribute('hidden'); // older profiles may have this set
-    sidebar_box.setAttribute('collapsed', 'false');
+    sidebar_box.removeAttribute('collapsed');
+    if (sidebar_splitter.getAttribute('state') == 'collapsed')
+      sidebar_splitter.removeAttribute('state');
     title_box.removeAttribute('hidden');
     sidebar_panels_splitter_box.removeAttribute('hidden'); // for older profiles
-    sidebar_panels_splitter_box.setAttribute('collapsed', 'false');
+    sidebar_panels_splitter_box.removeAttribute('collapsed');
     sidebar_splitter.removeAttribute('hidden');
     if (sidebar_box.firstChild != sidebar_panels_splitter) {
       debug("Showing the panels splitter");