diff -r 000000000000 -r 6474c204b198 browser/components/sessionstore/test/browser_485563.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/components/sessionstore/test/browser_485563.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,26 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+function test() {
+  /** Test for Bug 485563 **/
+
+  waitForExplicitFinish();
+
+  let uniqueValue = Math.random() + "\u2028Second line\u2029Second paragraph\u2027";
+
+  let tab = gBrowser.addTab();
+  whenBrowserLoaded(tab.linkedBrowser, function() {
+    ss.setTabValue(tab, "bug485563", uniqueValue);
+    let tabState = JSON.parse(ss.getTabState(tab));
+    is(tabState.extData["bug485563"], uniqueValue,
+       "unicode line separator wasn't over-encoded");
+    ss.deleteTabValue(tab, "bug485563");
+    ss.setTabState(tab, JSON.stringify(tabState));
+    is(ss.getTabValue(tab, "bug485563"), uniqueValue,
+       "unicode line separator was correctly preserved");
+
+    gBrowser.removeTab(tab);
+    finish();
+  });
+}