diff --git a/dom/indexedDB/test/browser.ini b/dom/indexedDB/test/browser.ini
index 4c158720caa1..85671568dca5 100644
--- a/dom/indexedDB/test/browser.ini
+++ b/dom/indexedDB/test/browser.ini
@@ -16,7 +16,6 @@ support-files =
 [browser_forgetThisSite.js]
 [browser_permissionsPromptAllow.js]
 [browser_permissionsPromptDeny.js]
-skip-if = e10s # bug 1220748 - Attempts to touch content docshell to set usePrivateBrowsing.
 [browser_permissionsPromptWorker.js]
 [browser_perwindow_privateBrowsing.js]
 [browser_bug839193.js]
diff --git a/dom/indexedDB/test/browserHelpers.js b/dom/indexedDB/test/browserHelpers.js
index 190777ea218c..c61c78943490 100644
--- a/dom/indexedDB/test/browserHelpers.js
+++ b/dom/indexedDB/test/browserHelpers.js
@@ -8,11 +8,6 @@ var testGenerator = testSteps();
 var testResult;
 var testException;
 
-function testFinishedCallback(result, exception)
-{
-  throw new Error("Bad testFinishedCallback!");
-}
-
 function runTest()
 {
   testGenerator.next();
@@ -29,7 +24,18 @@ function finishTestNow()
 function finishTest()
 {
   setTimeout(finishTestNow, 0);
-  setTimeout(testFinishedCallback, 0, testResult, testException);
+  setTimeout(() => {
+    if (window.testFinishedCallback)
+      window.testFinishedCallback(testResult, testException);
+    else {
+      let message;
+      if (testResult)
+        message = "ok";
+      else
+        message = testException;
+      window.parent.postMessage(message, "*");
+    }
+  }, 0);
 }
 
 function grabEventAndContinueHandler(event)
diff --git a/dom/indexedDB/test/browser_permissionsPromptDeny.js b/dom/indexedDB/test/browser_permissionsPromptDeny.js
index 54ecc52920db..264fd69a23a6 100644
--- a/dom/indexedDB/test/browser_permissionsPromptDeny.js
+++ b/dom/indexedDB/test/browser_permissionsPromptDeny.js
@@ -7,118 +7,113 @@ const testPageURL = "http://mochi.test:8888/browser/" +
   "dom/indexedDB/test/browser_permissionsPrompt.html";
 const notificationID = "indexedDB-permissions-prompt";
 
-function test()
-{
-  waitForExplicitFinish();
-  // We want the prompt.
+function setUsePrivateBrowsing(browser, val) {
+  if (!browser.isRemoteBrowser) {
+    browser.docShell.QueryInterface(Ci.nsILoadContext).usePrivateBrowsing = val;
+    return;
+  }
+
+  return ContentTask.spawn(browser, val, function* (val) {
+    docShell.QueryInterface(Ci.nsILoadContext).usePrivateBrowsing = val;
+  });
+};
+
+
+function promiseMessage(aMessage) {
+  return new Promise(function(resolve, reject) {
+    content.addEventListener("message", function messageListener(event) {
+      content.removeEventListener("message", messageListener);
+      is(event.data, aMessage, "received " + aMessage);
+      if (event.data == aMessage)
+        resolve();
+      else
+        reject();
+    });
+  });
+}
+
+add_task(function test1() {
   removePermission(testPageURL, "indexedDB");
-  executeSoon(test1);
-}
 
-function test1()
-{
   info("creating tab");
   gBrowser.selectedTab = gBrowser.addTab();
 
-  gBrowser.selectedBrowser.addEventListener("load", function () {
-    gBrowser.selectedBrowser.removeEventListener("load", arguments.callee, true);
-
-    setFinishedCallback(function(result, exception) {
-      ok(!result, "No database created");
-      is(exception, "InvalidStateError", "Correct exception");
-      is(getPermission(testPageURL, "indexedDB"),
-         Components.interfaces.nsIPermissionManager.DENY_ACTION,
-         "Correct permission set");
-      gBrowser.removeCurrentTab();
-      executeSoon(test2);
-    });
-
-    registerPopupEventHandler("popupshowing", function () {
-      ok(true, "prompt showing");
-    });
-    registerPopupEventHandler("popupshown", function () {
-      ok(true, "prompt shown");
-      triggerSecondaryCommand(this, 0);
-    });
-    registerPopupEventHandler("popuphidden", function () {
-      ok(true, "prompt hidden");
-    });
-
-  }, true);
-
   info("loading test page: " + testPageURL);
-  content.location = testPageURL;
-}
+  gBrowser.selectedBrowser.loadURI(testPageURL);
+  yield BrowserTestUtils.browserLoaded(gBrowser.selectedBrowser);
 
-function test2()
-{
-  info("creating tab");
+  registerPopupEventHandler("popupshowing", function () {
+    ok(true, "prompt showing");
+  });
+  registerPopupEventHandler("popupshown", function () {
+    ok(true, "prompt shown");
+    triggerSecondaryCommand(this, 0);
+  });
+  registerPopupEventHandler("popuphidden", function () {
+    ok(true, "prompt hidden");
+  });
+
+  yield promiseMessage("InvalidStateError");
+
+  is(getPermission(testPageURL, "indexedDB"),
+     Components.interfaces.nsIPermissionManager.DENY_ACTION,
+     "Correct permission set");
+  gBrowser.removeCurrentTab();
+});
+
+add_task(function test2() {
+  info("creating private tab");
   gBrowser.selectedTab = gBrowser.addTab();
-  gBrowser.selectedBrowser.docShell.QueryInterface(Ci.nsILoadContext).usePrivateBrowsing = true;
-
-  gBrowser.selectedBrowser.addEventListener("load", function () {
-    gBrowser.selectedBrowser.removeEventListener("load", arguments.callee, true);
-
-    setFinishedCallback(function(result, exception) {
-      ok(!result, "No database created");
-      is(exception, "InvalidStateError", "Correct exception");
-      is(getPermission(testPageURL, "indexedDB"),
-         Components.interfaces.nsIPermissionManager.DENY_ACTION,
-         "Correct permission set");
-      gBrowser.selectedBrowser.docShell.QueryInterface(Ci.nsILoadContext).usePrivateBrowsing = false;
-      unregisterAllPopupEventHandlers();
-      gBrowser.removeCurrentTab();
-      executeSoon(test3);
-    });
-
-    registerPopupEventHandler("popupshowing", function () {
-      ok(false, "prompt showing");
-    });
-    registerPopupEventHandler("popupshown", function () {
-      ok(false, "prompt shown");
-    });
-    registerPopupEventHandler("popuphidden", function () {
-      ok(false, "prompt hidden");
-    });
-
-  }, true);
+  yield setUsePrivateBrowsing(gBrowser.selectedBrowser, true);
 
   info("loading test page: " + testPageURL);
-  content.location = testPageURL;
-}
+  gBrowser.selectedBrowser.loadURI(testPageURL);
+  yield BrowserTestUtils.browserLoaded(gBrowser.selectedBrowser);
 
-function test3()
-{
+  registerPopupEventHandler("popupshowing", function () {
+    ok(false, "prompt showing");
+  });
+  registerPopupEventHandler("popupshown", function () {
+    ok(false, "prompt shown");
+  });
+  registerPopupEventHandler("popuphidden", function () {
+    ok(false, "prompt hidden");
+  });
+
+  yield promiseMessage("InvalidStateError");
+
+  is(getPermission(testPageURL, "indexedDB"),
+     Components.interfaces.nsIPermissionManager.DENY_ACTION,
+     "Correct permission set");
+  unregisterAllPopupEventHandlers();
+  yield setUsePrivateBrowsing(gBrowser.selectedBrowser, false);
+  gBrowser.removeCurrentTab();
+});
+
+add_task(function test3() {
   info("creating tab");
   gBrowser.selectedTab = gBrowser.addTab();
 
-  gBrowser.selectedBrowser.addEventListener("load", function () {
-    gBrowser.selectedBrowser.removeEventListener("load", arguments.callee, true);
-
-    setFinishedCallback(function(result, exception) {
-      ok(!result, "No database created");
-      is(exception, "InvalidStateError", "Correct exception");
-      is(getPermission(testPageURL, "indexedDB"),
-         Components.interfaces.nsIPermissionManager.DENY_ACTION,
-         "Correct permission set");
-      gBrowser.removeCurrentTab();
-      unregisterAllPopupEventHandlers();
-      removePermission(testPageURL, "indexedDB");
-      executeSoon(finish);
-    });
-
-    registerPopupEventHandler("popupshowing", function () {
-      ok(false, "Shouldn't show a popup this time");
-    });
-    registerPopupEventHandler("popupshown", function () {
-      ok(false, "Shouldn't show a popup this time");
-    });
-    registerPopupEventHandler("popuphidden", function () {
-      ok(false, "Shouldn't show a popup this time");
-    });
-
-  }, true);
-
   info("loading test page: " + testPageURL);
-  content.location = testPageURL;
-}
+  gBrowser.selectedBrowser.loadURI(testPageURL);
+  yield BrowserTestUtils.browserLoaded(gBrowser.selectedBrowser);
+
+  registerPopupEventHandler("popupshowing", function () {
+    ok(false, "Shouldn't show a popup this time");
+  });
+  registerPopupEventHandler("popupshown", function () {
+    ok(false, "Shouldn't show a popup this time");
+  });
+  registerPopupEventHandler("popuphidden", function () {
+    ok(false, "Shouldn't show a popup this time");
+  });
+
+  yield promiseMessage("InvalidStateError");
+
+  is(getPermission(testPageURL, "indexedDB"),
+     Components.interfaces.nsIPermissionManager.DENY_ACTION,
+     "Correct permission set");
+  gBrowser.removeCurrentTab();
+  unregisterAllPopupEventHandlers();
+  removePermission(testPageURL, "indexedDB");
+});