diff -r 000000000000 -r 6474c204b198 dom/browser-element/mochitest/browserElement_TopBarrier.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/browser-element/mochitest/browserElement_TopBarrier.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/ */
+
+// Test that an <iframe mozbrowser> is a window.{top,parent,frameElement} barrier.
+"use strict";
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+
+var iframe;
+function runTest() {
+  iframe = document.createElement('iframe');
+  iframe.addEventListener('mozbrowserloadend', function() {
+    try {
+      outerIframeLoaded();
+    } catch(e) {
+      dump("Got error: " + e + '\n');
+    }
+  });
+  SpecialPowers.wrap(iframe).mozbrowser = true;
+  iframe.src = 'data:text/html,Outer iframe <iframe id="inner-iframe"></iframe>';
+  // For kicks, this test uses a display:none iframe.  This shouldn't make a
+  // difference in anything.
+  iframe.style.display = 'none';
+  document.body.appendChild(iframe);
+}
+
+var numMsgReceived = 0;
+function outerIframeLoaded() {
+  var injectedScript =
+    "data:,function is(a, b, desc) {                                     \
+      if (a == b) {                                                      \
+        sendAsyncMessage('test:test-pass', desc);                        \
+      } else {                                                           \
+        sendAsyncMessage('test:test-fail', desc + ' ' + a + ' != ' + b); \
+      }                                                                  \
+    }                                                                    \
+    is(content.window.top, content.window, 'top');                       \
+    is(content.window.content, content.window, 'content');               \
+    is(content.window.parent, content.window, 'parent');                 \
+    is(content.window.frameElement, null, 'frameElement');               \
+    var innerIframe = content.document.getElementById('inner-iframe');   \
+    var innerWindow = innerIframe.contentWindow;                         \
+    is(innerWindow.top, content.window, 'inner top');                    \
+    is(innerWindow.content, content.window, 'inner content');            \
+    is(innerWindow.parent, content.window, 'inner parent');              \
+    is(innerWindow.frameElement, innerIframe, 'inner frameElement');"
+
+  var mm = SpecialPowers.getBrowserFrameMessageManager(iframe);
+
+  function onRecvTestPass(msg) {
+    numMsgReceived++;
+    ok(true, msg.json);
+  }
+  mm.addMessageListener('test:test-pass', onRecvTestPass);
+
+  function onRecvTestFail(msg) {
+    numMsgReceived++;
+    ok(false, msg.json);
+  }
+  mm.addMessageListener('test:test-fail', onRecvTestFail);
+
+  mm.loadFrameScript(injectedScript, /* allowDelayedLoad = */ false);
+
+  waitForMessages(6);
+}
+
+function waitForMessages(num) {
+  if (numMsgReceived < num) {
+    SimpleTest.executeSoon(function() { waitForMessages(num); });
+    return;
+  }
+
+  SimpleTest.finish();
+}
+
+addEventListener('testready', runTest);