diff -r 000000000000 -r 6474c204b198 browser/components/sessionstore/test/browser_capabilities.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/components/sessionstore/test/browser_capabilities.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,78 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * These tests ensures that disabling features by flipping nsIDocShell.allow*
+ * properties are (re)stored as disabled. Disallowed features must be
+ * re-enabled when the tab is re-used by another tab restoration.
+ */
+add_task(function docshell_capabilities() {
+  let tab = yield createTab();
+  let browser = tab.linkedBrowser;
+  let docShell = browser.docShell;
+
+  // Get the list of capabilities for docShells.
+  let flags = Object.keys(docShell).filter(k => k.startsWith("allow"));
+
+  // Check that everything is allowed by default for new tabs.
+  let state = JSON.parse(ss.getTabState(tab));
+  ok(!("disallow" in state), "everything allowed by default");
+  ok(flags.every(f => docShell[f]), "all flags set to true");
+
+  // Flip a couple of allow* flags.
+  docShell.allowImages = false;
+  docShell.allowMetaRedirects = false;
+
+  // Now reload the document to ensure that these capabilities
+  // are taken into account.
+  browser.reload();
+  yield promiseBrowserLoaded(browser);
+
+  // Flush to make sure chrome received all data.
+  SyncHandlers.get(browser).flush();
+
+  // Check that we correctly save disallowed features.
+  let disallowedState = JSON.parse(ss.getTabState(tab));
+  let disallow = new Set(disallowedState.disallow.split(","));
+  ok(disallow.has("Images"), "images not allowed");
+  ok(disallow.has("MetaRedirects"), "meta redirects not allowed");
+  is(disallow.size, 2, "two capabilities disallowed");
+
+  // Reuse the tab to restore a new, clean state into it.
+  ss.setTabState(tab, JSON.stringify({ entries: [{url: "about:robots"}] }));
+  yield promiseTabRestored(tab);
+
+  // Flush to make sure chrome received all data.
+  SyncHandlers.get(browser).flush();
+
+  // After restoring disallowed features must be available again.
+  state = JSON.parse(ss.getTabState(tab));
+  ok(!("disallow" in state), "everything allowed again");
+  ok(flags.every(f => docShell[f]), "all flags set to true");
+
+  // Restore the state with disallowed features.
+  ss.setTabState(tab, JSON.stringify(disallowedState));
+  yield promiseTabRestored(tab);
+
+  // Check that docShell flags are set.
+  ok(!docShell.allowImages, "images not allowed");
+  ok(!docShell.allowMetaRedirects, "meta redirects not allowed");
+
+  // Check that we correctly restored features as disabled.
+  state = JSON.parse(ss.getTabState(tab));
+  disallow = new Set(state.disallow.split(","));
+  ok(disallow.has("Images"), "images not allowed anymore");
+  ok(disallow.has("MetaRedirects"), "meta redirects not allowed anymore");
+  is(disallow.size, 2, "two capabilities disallowed");
+
+  // Clean up after ourselves.
+  gBrowser.removeTab(tab);
+});
+
+function createTab() {
+  let tab = gBrowser.addTab("about:mozilla");
+  let browser = tab.linkedBrowser;
+  return promiseBrowserLoaded(browser).then(() => tab);
+}