--- a/browser/base/content/test/about/browser.ini
+++ b/browser/base/content/test/about/browser.ini
@@ -4,16 +4,18 @@ support-files =
   head.js
   print_postdata.sjs
   searchSuggestionEngine.sjs
   searchSuggestionEngine.xml
   test_bug959531.html
   POSTSearchEngine.xml
 
 [browser_aboutCertError.js]
+support-files =
+  dummy_page.html
 [browser_aboutHome_imitate.js]
 [browser_aboutHome_input.js]
 skip-if = true # Bug 1409054 to remove; previously skipped for intermittents, e.g., Bug 1399648
 [browser_aboutHome_search_POST.js]
 [browser_aboutHome_search_composing.js]
 skip-if = !debug && (os == "mac" || (os == "linux" && bits == 32)) # Bug 1400491, bug 1399648
 [browser_aboutHome_search_searchbar.js]
 [browser_aboutHome_search_suggestion.js]

--- a/browser/base/content/test/about/browser_aboutCertError.js
+++ b/browser/base/content/test/about/browser_aboutCertError.js
@@ -1,114 +1,160 @@
 /* Any copyright is dedicated to the Public Domain.
  * http://creativecommons.org/publicdomain/zero/1.0/ */
 
 "use strict";
 
 // This is testing the aboutCertError page (Bug 1207107).
 
 const GOOD_PAGE = "https://example.com/";
+const GOOD_PAGE_2 = "https://example.org/";
+const DUMMY_PAGE = getRootDirectory(gTestPath).replace("chrome://mochitests/content", GOOD_PAGE) + "dummy_page.html";
 const BAD_CERT = "https://expired.example.com/";
 const UNKNOWN_ISSUER = "https://self-signed.example.com ";
 const BAD_STS_CERT = "https://badchain.include-subdomains.pinning.example.com:443";
 const {TabStateFlusher} = ChromeUtils.import("resource:///modules/sessionstore/TabStateFlusher.jsm", {});
 const ss = Cc["@mozilla.org/browser/sessionstore;1"].getService(Ci.nsISessionStore);
 
+function injectErrorPageFrame(tab, src) {
+  return ContentTask.spawn(tab.linkedBrowser, {frameSrc: src}, async function({frameSrc}) {
+    let loaded = ContentTaskUtils.waitForEvent(content.wrappedJSObject, "DOMFrameContentLoaded");
+    let iframe = content.document.createElement("iframe");
+    iframe.src = frameSrc;
+    content.document.body.appendChild(iframe);
+    await loaded;
+    // We will have race conditions when accessing the frame content after setting a src,
+    // so we can't wait for AboutNetErrorLoad. Let's wait for the certerror class to
+    // appear instead (which should happen at the same time as AboutNetErrorLoad).
+    await ContentTaskUtils.waitForCondition(() =>
+      iframe.contentDocument.body.classList.contains("certerror"));
+  });
+}
+
+async function openErrorPage(src, useFrame) {
+  let tab;
+  if (useFrame) {
+    info("Loading cert error page in an iframe");
+    tab = await BrowserTestUtils.openNewForegroundTab(gBrowser, DUMMY_PAGE);
+    await injectErrorPageFrame(tab, src);
+  } else {
+    let certErrorLoaded;
+    tab = await BrowserTestUtils.openNewForegroundTab(gBrowser, () => {
+      gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, src);
+      let browser = gBrowser.selectedBrowser;
+      certErrorLoaded = BrowserTestUtils.waitForErrorPage(browser);
+    }, false);
+    info("Loading and waiting for the cert error");
+    await certErrorLoaded;
+  }
+
+  return tab;
+}
+
 add_task(async function checkReturnToAboutHome() {
   info("Loading a bad cert page directly and making sure 'return to previous page' goes to about:home");
-  let browser;
-  let certErrorLoaded;
-  let tab = await BrowserTestUtils.openNewForegroundTab(gBrowser, () => {
-    gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, BAD_CERT);
-    browser = gBrowser.selectedBrowser;
-    certErrorLoaded = BrowserTestUtils.waitForErrorPage(browser);
-  }, false);
+  for (let useFrame of [false, true]) {
+    let tab = await openErrorPage(BAD_CERT, useFrame);
+    let browser = tab.linkedBrowser;
 
-  info("Loading and waiting for the cert error");
-  await certErrorLoaded;
+    is(browser.webNavigation.canGoBack, false, "!webNavigation.canGoBack");
+    is(browser.webNavigation.canGoForward, false, "!webNavigation.canGoForward");
 
-  is(browser.webNavigation.canGoBack, false, "!webNavigation.canGoBack");
-  is(browser.webNavigation.canGoForward, false, "!webNavigation.canGoForward");
+    // Populate the shistory entries manually, since it happens asynchronously
+    // and the following tests will be too soon otherwise.
+    await TabStateFlusher.flush(browser);
+    let {entries} = JSON.parse(ss.getTabState(tab));
+    is(entries.length, 1, "there is one shistory entry");
 
-  // Populate the shistory entries manually, since it happens asynchronously
-  // and the following tests will be too soon otherwise.
-  await TabStateFlusher.flush(browser);
-  let {entries} = JSON.parse(ss.getTabState(tab));
-  is(entries.length, 1, "there is one shistory entry");
+    info("Clicking the go back button on about:certerror");
+    await ContentTask.spawn(browser, {frame: useFrame}, async function({frame}) {
+      let doc = frame ? content.document.querySelector("iframe").contentDocument : content.document;
+
+      let returnButton = doc.getElementById("returnButton");
+      if (!frame) {
+        is(returnButton.getAttribute("autofocus"), "true", "returnButton has autofocus");
+      }
+      returnButton.click();
 
-  info("Clicking the go back button on about:certerror");
-  await ContentTask.spawn(browser, null, async function() {
-    let doc = content.document;
-    let returnButton = doc.getElementById("returnButton");
-    is(returnButton.getAttribute("autofocus"), "true", "returnButton has autofocus");
-    returnButton.click();
+      await ContentTaskUtils.waitForEvent(this, "pageshow", true);
+    });
 
-    await ContentTaskUtils.waitForEvent(this, "pageshow", true);
-  });
+    is(browser.webNavigation.canGoBack, true, "webNavigation.canGoBack");
+    is(browser.webNavigation.canGoForward, false, "!webNavigation.canGoForward");
+    is(gBrowser.currentURI.spec, "about:home", "Went back");
 
-  is(browser.webNavigation.canGoBack, true, "webNavigation.canGoBack");
-  is(browser.webNavigation.canGoForward, false, "!webNavigation.canGoForward");
-  is(gBrowser.currentURI.spec, "about:home", "Went back");
-
-  await BrowserTestUtils.removeTab(gBrowser.selectedTab);
+    await BrowserTestUtils.removeTab(gBrowser.selectedTab);
+  }
 });
 
 add_task(async function checkReturnToPreviousPage() {
   info("Loading a bad cert page and making sure 'return to previous page' goes back");
-  let tab = await BrowserTestUtils.openNewForegroundTab(gBrowser, GOOD_PAGE);
-  let browser = gBrowser.selectedBrowser;
+  for (let useFrame of [false, true]) {
+    let tab;
+    let browser;
+    if (useFrame) {
+      tab = await BrowserTestUtils.openNewForegroundTab(gBrowser, GOOD_PAGE);
+      browser = tab.linkedBrowser;
 
-  info("Loading and waiting for the cert error");
-  let certErrorLoaded = BrowserTestUtils.waitForErrorPage(browser);
-  BrowserTestUtils.loadURI(browser, BAD_CERT);
-  await certErrorLoaded;
+      BrowserTestUtils.loadURI(browser, GOOD_PAGE_2);
+      await BrowserTestUtils.browserLoaded(browser, false, GOOD_PAGE_2);
+      await injectErrorPageFrame(tab, BAD_CERT);
+    } else {
+      tab = await BrowserTestUtils.openNewForegroundTab(gBrowser, GOOD_PAGE);
+      browser = gBrowser.selectedBrowser;
 
-  is(browser.webNavigation.canGoBack, true, "webNavigation.canGoBack");
-  is(browser.webNavigation.canGoForward, false, "!webNavigation.canGoForward");
+      info("Loading and waiting for the cert error");
+      let certErrorLoaded = BrowserTestUtils.waitForErrorPage(browser);
+      BrowserTestUtils.loadURI(browser, BAD_CERT);
+      await certErrorLoaded;
+    }
 
-  // Populate the shistory entries manually, since it happens asynchronously
-  // and the following tests will be too soon otherwise.
-  await TabStateFlusher.flush(browser);
-  let {entries} = JSON.parse(ss.getTabState(tab));
-  is(entries.length, 2, "there are two shistory entries");
+    is(browser.webNavigation.canGoBack, true, "webNavigation.canGoBack");
+    is(browser.webNavigation.canGoForward, false, "!webNavigation.canGoForward");
+
+    // Populate the shistory entries manually, since it happens asynchronously
+    // and the following tests will be too soon otherwise.
+    await TabStateFlusher.flush(browser);
+    let {entries} = JSON.parse(ss.getTabState(tab));
+    is(entries.length, 2, "there are two shistory entries");
 
-  info("Clicking the go back button on about:certerror");
-  await ContentTask.spawn(browser, null, async function() {
-    let doc = content.document;
-    let returnButton = doc.getElementById("returnButton");
-    returnButton.click();
+    info("Clicking the go back button on about:certerror");
+    await ContentTask.spawn(browser, {frame: useFrame}, async function({frame}) {
+      let doc = frame ? content.document.querySelector("iframe").contentDocument : content.document;
+      let returnButton = doc.getElementById("returnButton");
+      returnButton.click();
 
-    await ContentTaskUtils.waitForEvent(this, "pageshow", true);
-  });
+      await ContentTaskUtils.waitForEvent(this, "pageshow", true);
+    });
 
-  is(browser.webNavigation.canGoBack, false, "!webNavigation.canGoBack");
-  is(browser.webNavigation.canGoForward, true, "webNavigation.canGoForward");
-  is(gBrowser.currentURI.spec, GOOD_PAGE, "Went back");
+    is(browser.webNavigation.canGoBack, false, "!webNavigation.canGoBack");
+    is(browser.webNavigation.canGoForward, true, "webNavigation.canGoForward");
+    is(gBrowser.currentURI.spec, GOOD_PAGE, "Went back");
 
-  await BrowserTestUtils.removeTab(gBrowser.selectedTab);
+    await BrowserTestUtils.removeTab(gBrowser.selectedTab);
+  }
 });
 
 add_task(async function checkBadStsCert() {
   info("Loading a badStsCert and making sure exception button doesn't show up");
-  await BrowserTestUtils.openNewForegroundTab(gBrowser, GOOD_PAGE);
-  let browser = gBrowser.selectedBrowser;
 
-  info("Loading and waiting for the cert error");
-  let certErrorLoaded = BrowserTestUtils.waitForErrorPage(browser);
-  BrowserTestUtils.loadURI(browser, BAD_STS_CERT);
-  await certErrorLoaded;
+  for (let useFrame of [false, true]) {
+    let tab = await openErrorPage(BAD_STS_CERT, useFrame);
+    let browser = tab.linkedBrowser;
 
-  let exceptionButtonHidden = await ContentTask.spawn(browser, null, async function() {
-    let doc = content.document;
-    let exceptionButton = doc.getElementById("exceptionDialogButton");
-    return exceptionButton.hidden;
-  });
-  ok(exceptionButtonHidden, "Exception button is hidden");
+    let exceptionButtonHidden = await ContentTask.spawn(browser, {frame: useFrame}, async function({frame}) {
+      let doc = frame ? content.document.querySelector("iframe").contentDocument : content.document;
+      let exceptionButton = doc.getElementById("exceptionDialogButton");
+      return exceptionButton.hidden;
+    });
 
-  await BrowserTestUtils.removeTab(gBrowser.selectedTab);
+    ok(exceptionButtonHidden, "Exception button is hidden");
+
+    await BrowserTestUtils.removeTab(gBrowser.selectedTab);
+  }
 });
 
 // This checks that the appinfo.appBuildID starts with a date string,
 // which is required for the misconfigured system time check.
 add_task(async function checkAppBuildIDIsDate() {
   let appBuildID = Services.appinfo.appBuildID;
   let year = parseInt(appBuildID.substr(0, 4), 10);
   let month = parseInt(appBuildID.substr(4, 2), 10);
@@ -216,165 +262,152 @@ add_task(async function checkWrongSystem
 
   is(message.divDisplay, "none", "Wrong time message information is not visible");
 
   await BrowserTestUtils.removeTab(gBrowser.selectedTab);
 }).skip(); // Skipping because of bug 1414804.
 
 add_task(async function checkAdvancedDetails() {
   info("Loading a bad cert page and verifying the main error and advanced details section");
-  let browser;
-  let certErrorLoaded;
-  await BrowserTestUtils.openNewForegroundTab(gBrowser, () => {
-    gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, BAD_CERT);
-    browser = gBrowser.selectedBrowser;
-    certErrorLoaded = BrowserTestUtils.waitForErrorPage(browser);
-  }, false);
+  for (let useFrame of [false, true]) {
+    let tab = await openErrorPage(BAD_CERT, useFrame);
+    let browser = tab.linkedBrowser;
 
-  info("Loading and waiting for the cert error");
-  await certErrorLoaded;
+    let message = await ContentTask.spawn(browser, {frame: useFrame}, async function({frame}) {
+      let doc = frame ? content.document.querySelector("iframe").contentDocument : content.document;
+
+      let shortDescText = doc.getElementById("errorShortDescText");
+      info("Main error text: " + shortDescText.textContent);
+      ok(shortDescText.textContent.includes("expired.example.com"),
+         "Should list hostname in error message.");
 
-  let message = await ContentTask.spawn(browser, null, async function() {
-    let doc = content.document;
-    let shortDescText = doc.getElementById("errorShortDescText");
-    info("Main error text: " + shortDescText.textContent);
-    ok(shortDescText.textContent.includes("expired.example.com"),
-       "Should list hostname in error message.");
+      let advancedButton = doc.getElementById("advancedButton");
+      advancedButton.click();
+      let el = doc.getElementById("errorCode");
+      return { textContent: el.textContent, tagName: el.tagName };
+    });
+    is(message.textContent, "SEC_ERROR_EXPIRED_CERTIFICATE",
+       "Correct error message found");
+    is(message.tagName, "a", "Error message is a link");
 
-    let advancedButton = doc.getElementById("advancedButton");
-    advancedButton.click();
-    let el = doc.getElementById("errorCode");
-    return { textContent: el.textContent, tagName: el.tagName };
-  });
-  is(message.textContent, "SEC_ERROR_EXPIRED_CERTIFICATE",
-     "Correct error message found");
-  is(message.tagName, "a", "Error message is a link");
+    message = await ContentTask.spawn(browser, {frame: useFrame}, async function({frame}) {
+      let doc = frame ? content.document.querySelector("iframe").contentDocument : content.document;
 
-  message = await ContentTask.spawn(browser, null, async function() {
-    let doc = content.document;
-    let errorCode = doc.getElementById("errorCode");
-    errorCode.click();
-    let div = doc.getElementById("certificateErrorDebugInformation");
-    let text = doc.getElementById("certificateErrorText");
+      let errorCode = doc.getElementById("errorCode");
+      errorCode.click();
+      let div = doc.getElementById("certificateErrorDebugInformation");
+      let text = doc.getElementById("certificateErrorText");
 
-    let serhelper = Cc["@mozilla.org/network/serialization-helper;1"]
-                     .getService(Ci.nsISerializationHelper);
-    let serializable =  docShell.failedChannel.securityInfo
-                                .QueryInterface(Ci.nsITransportSecurityInfo)
-                                .QueryInterface(Ci.nsISerializable);
-    let serializedSecurityInfo = serhelper.serializeToString(serializable);
-    return {
-      divDisplay: content.getComputedStyle(div).display,
-      text: text.textContent,
-      securityInfoAsString: serializedSecurityInfo
-    };
-  });
-  isnot(message.divDisplay, "none", "Debug information is visible");
-  ok(message.text.includes(BAD_CERT), "Correct URL found");
-  ok(message.text.includes("Certificate has expired"),
-     "Correct error message found");
-  ok(message.text.includes("HTTP Strict Transport Security: false"),
-     "Correct HSTS value found");
-  ok(message.text.includes("HTTP Public Key Pinning: false"),
-     "Correct HPKP value found");
-  let certChain = getCertChain(message.securityInfoAsString);
-  ok(message.text.includes(certChain), "Found certificate chain");
+      let serhelper = Cc["@mozilla.org/network/serialization-helper;1"]
+                       .getService(Ci.nsISerializationHelper);
+      let serializable =  doc.docShell.failedChannel.securityInfo
+                                      .QueryInterface(Ci.nsITransportSecurityInfo)
+                                      .QueryInterface(Ci.nsISerializable);
+      let serializedSecurityInfo = serhelper.serializeToString(serializable);
+      return {
+        divDisplay: content.getComputedStyle(div).display,
+        text: text.textContent,
+        securityInfoAsString: serializedSecurityInfo
+      };
+    });
+    isnot(message.divDisplay, "none", "Debug information is visible");
+    ok(message.text.includes(BAD_CERT), "Correct URL found");
+    ok(message.text.includes("Certificate has expired"),
+       "Correct error message found");
+    ok(message.text.includes("HTTP Strict Transport Security: false"),
+       "Correct HSTS value found");
+    ok(message.text.includes("HTTP Public Key Pinning: false"),
+       "Correct HPKP value found");
+    let certChain = getCertChain(message.securityInfoAsString);
+    ok(message.text.includes(certChain), "Found certificate chain");
 
-  await BrowserTestUtils.removeTab(gBrowser.selectedTab);
+    await BrowserTestUtils.removeTab(gBrowser.selectedTab);
+  }
 });
 
 add_task(async function checkAdvancedDetailsForHSTS() {
   info("Loading a bad STS cert page and verifying the advanced details section");
-  let browser;
-  let certErrorLoaded;
-  await BrowserTestUtils.openNewForegroundTab(gBrowser, () => {
-    gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, BAD_STS_CERT);
-    browser = gBrowser.selectedBrowser;
-    certErrorLoaded = BrowserTestUtils.waitForErrorPage(browser);
-  }, false);
+  for (let useFrame of [false, true]) {
+    let tab = await openErrorPage(BAD_STS_CERT, useFrame);
+    let browser = tab.linkedBrowser;
 
-  info("Loading and waiting for the cert error");
-  await certErrorLoaded;
+    let message = await ContentTask.spawn(browser, {frame: useFrame}, async function({frame}) {
+      let doc = frame ? content.document.querySelector("iframe").contentDocument : content.document;
 
-  let message = await ContentTask.spawn(browser, null, async function() {
-    let doc = content.document;
-    let advancedButton = doc.getElementById("advancedButton");
-    advancedButton.click();
-    let ec = doc.getElementById("errorCode");
-    let cdl = doc.getElementById("cert_domain_link");
-    return {
-      ecTextContent: ec.textContent,
-      ecTagName: ec.tagName,
-      cdlTextContent: cdl.textContent,
-      cdlTagName: cdl.tagName
-    };
-  });
+      let advancedButton = doc.getElementById("advancedButton");
+      advancedButton.click();
+      let ec = doc.getElementById("errorCode");
+      let cdl = doc.getElementById("cert_domain_link");
+      return {
+        ecTextContent: ec.textContent,
+        ecTagName: ec.tagName,
+        cdlTextContent: cdl.textContent,
+        cdlTagName: cdl.tagName
+      };
+    });
+
+    const badStsUri = Services.io.newURI(BAD_STS_CERT);
+    is(message.ecTextContent, "SSL_ERROR_BAD_CERT_DOMAIN",
+       "Correct error message found");
+    is(message.ecTagName, "a", "Error message is a link");
+    const url = badStsUri.prePath.slice(badStsUri.prePath.indexOf(".") + 1);
+    is(message.cdlTextContent, url,
+       "Correct cert_domain_link contents found");
+    is(message.cdlTagName, "a", "cert_domain_link is a link");
+
+    message = await ContentTask.spawn(browser, {frame: useFrame}, async function({frame}) {
+      let doc = frame ? content.document.querySelector("iframe").contentDocument : content.document;
 
-  const badStsUri = Services.io.newURI(BAD_STS_CERT);
-  is(message.ecTextContent, "SSL_ERROR_BAD_CERT_DOMAIN",
-     "Correct error message found");
-  is(message.ecTagName, "a", "Error message is a link");
-  const url = badStsUri.prePath.slice(badStsUri.prePath.indexOf(".") + 1);
-  is(message.cdlTextContent, url,
-     "Correct cert_domain_link contents found");
-  is(message.cdlTagName, "a", "cert_domain_link is a link");
-
-  message = await ContentTask.spawn(browser, null, async function() {
-    let doc = content.document;
-    let errorCode = doc.getElementById("errorCode");
-    errorCode.click();
-    let div = doc.getElementById("certificateErrorDebugInformation");
-    let text = doc.getElementById("certificateErrorText");
+      let errorCode = doc.getElementById("errorCode");
+      errorCode.click();
+      let div = doc.getElementById("certificateErrorDebugInformation");
+      let text = doc.getElementById("certificateErrorText");
 
-    let serhelper = Cc["@mozilla.org/network/serialization-helper;1"]
-                     .getService(Ci.nsISerializationHelper);
-    let serializable =  docShell.failedChannel.securityInfo
-                                .QueryInterface(Ci.nsITransportSecurityInfo)
-                                .QueryInterface(Ci.nsISerializable);
-    let serializedSecurityInfo = serhelper.serializeToString(serializable);
-    return {
-      divDisplay: content.getComputedStyle(div).display,
-      text: text.textContent,
-      securityInfoAsString: serializedSecurityInfo
-    };
-  });
-  isnot(message.divDisplay, "none", "Debug information is visible");
-  ok(message.text.includes(badStsUri.spec), "Correct URL found");
-  ok(message.text.includes("requested domain name does not match the server\u2019s certificate"),
-     "Correct error message found");
-  ok(message.text.includes("HTTP Strict Transport Security: false"),
-     "Correct HSTS value found");
-  ok(message.text.includes("HTTP Public Key Pinning: true"),
-     "Correct HPKP value found");
-  let certChain = getCertChain(message.securityInfoAsString);
-  ok(message.text.includes(certChain), "Found certificate chain");
+      let serhelper = Cc["@mozilla.org/network/serialization-helper;1"]
+                       .getService(Ci.nsISerializationHelper);
+      let serializable =  doc.docShell.failedChannel.securityInfo
+                                      .QueryInterface(Ci.nsITransportSecurityInfo)
+                                      .QueryInterface(Ci.nsISerializable);
+      let serializedSecurityInfo = serhelper.serializeToString(serializable);
+      return {
+        divDisplay: content.getComputedStyle(div).display,
+        text: text.textContent,
+        securityInfoAsString: serializedSecurityInfo
+      };
+    });
+    isnot(message.divDisplay, "none", "Debug information is visible");
+    ok(message.text.includes(badStsUri.spec), "Correct URL found");
+    ok(message.text.includes("requested domain name does not match the server\u2019s certificate"),
+       "Correct error message found");
+    ok(message.text.includes("HTTP Strict Transport Security: false"),
+       "Correct HSTS value found");
+    ok(message.text.includes("HTTP Public Key Pinning: true"),
+       "Correct HPKP value found");
+    let certChain = getCertChain(message.securityInfoAsString);
+    ok(message.text.includes(certChain), "Found certificate chain");
 
-  await BrowserTestUtils.removeTab(gBrowser.selectedTab);
+    await BrowserTestUtils.removeTab(gBrowser.selectedTab);
+  }
 });
 
 add_task(async function checkUnknownIssuerLearnMoreLink() {
   info("Loading a cert error for self-signed pages and checking the correct link is shown");
-  let browser;
-  let certErrorLoaded;
-  await BrowserTestUtils.openNewForegroundTab(gBrowser, () => {
-    gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, UNKNOWN_ISSUER);
-    browser = gBrowser.selectedBrowser;
-    certErrorLoaded = BrowserTestUtils.waitForErrorPage(browser);
-  }, false);
+  for (let useFrame of [false, true]) {
+    let tab = await openErrorPage(UNKNOWN_ISSUER, useFrame);
+    let browser = tab.linkedBrowser;
 
-  info("Loading and waiting for the cert error");
-  await certErrorLoaded;
+    let href = await ContentTask.spawn(browser, {frame: useFrame}, async function({frame}) {
+      let doc = frame ? content.document.querySelector("iframe").contentDocument : content.document;
+      let learnMoreLink = doc.getElementById("learnMoreLink");
+      return learnMoreLink.href;
+    });
+    ok(href.endsWith("security-error"), "security-error in the Learn More URL");
 
-  let href = await ContentTask.spawn(browser, null, async function() {
-    let learnMoreLink = content.document.getElementById("learnMoreLink");
-    return learnMoreLink.href;
-  });
-  ok(href.endsWith("security-error"), "security-error in the Learn More URL");
-
-  await BrowserTestUtils.removeTab(gBrowser.selectedTab);
+    await BrowserTestUtils.removeTab(gBrowser.selectedTab);
+  }
 });
 
 function getCertChain(securityInfoAsString) {
   let certChain = "";
   const serhelper = Cc["@mozilla.org/network/serialization-helper;1"]
                        .getService(Ci.nsISerializationHelper);
   let securityInfo = serhelper.deserializeObject(securityInfoAsString);
   securityInfo.QueryInterface(Ci.nsITransportSecurityInfo);

new file mode 100644
--- /dev/null
+++ b/browser/base/content/test/about/dummy_page.html
@@ -0,0 +1,9 @@
+<html>
+<head>
+<title>Dummy test page</title>
+<meta http-equiv="Content-Type" content="text/html;charset=utf-8"></meta>
+</head>
+<body>
+<p>Dummy test page</p>
+</body>
+</html>