--- a/browser/base/content/browser.js
+++ b/browser/base/content/browser.js
@@ -2843,34 +2843,16 @@ var BrowserOnClick = {
       case "captive-portal-login-success":
         // Broadcast when a captive portal is freed so that error pages
         // can refresh themselves.
         window.messageManager.broadcastAsyncMessage("Browser:CaptivePortalFreed");
       break;
     }
   },
 
-  handleEvent(event) {
-    if (!event.isTrusted || // Don't trust synthetic events
-        event.button == 2) {
-      return;
-    }
-
-    let originalTarget = event.originalTarget;
-    let ownerDoc = originalTarget.ownerDocument;
-    if (!ownerDoc) {
-      return;
-    }
-
-    if (gMultiProcessBrowser &&
-        ownerDoc.documentURI.toLowerCase() == "about:newtab") {
-      this.onE10sAboutNewTab(event, ownerDoc);
-    }
-  },
-
   receiveMessage(msg) {
     switch (msg.name) {
       case "Browser:CertExceptionError":
         this.onCertError(msg.target, msg.data.elementId,
                          msg.data.isTopFrame, msg.data.location,
                          msg.data.securityInfoAsString);
       break;
       case "Browser:OpenCaptivePortalPage":
@@ -3054,38 +3036,16 @@ var BrowserOnClick = {
             secHistogram.add(nsISecTel[bucketName + "IGNORE_WARNING"]);
           }
           this.ignoreWarningButton(reason);
         }
         break;
     }
   },
 
-  /**
-   * This functions prevents navigation from happening directly through the <a>
-   * link in about:newtab (which is loaded in the parent and therefore would load
-   * the next page also in the parent) and instructs the browser to open the url
-   * in the current tab which will make it update the remoteness of the tab.
-   */
-  onE10sAboutNewTab(event, ownerDoc) {
-    let isTopFrame = (ownerDoc.defaultView.parent === ownerDoc.defaultView);
-    if (!isTopFrame) {
-      return;
-    }
-
-    let anchorTarget = event.originalTarget.parentNode;
-
-    if (anchorTarget instanceof HTMLAnchorElement &&
-        anchorTarget.classList.contains("newtab-link")) {
-      event.preventDefault();
-      let where = whereToOpenLink(event, false, false);
-      openLinkIn(anchorTarget.href, where, { charset: ownerDoc.characterSet, referrerURI: ownerDoc.documentURIObject });
-    }
-  },
-
   ignoreWarningButton(reason) {
     // Allow users to override and continue through to the site,
     // but add a notify bar as a reminder, so that they don't lose
     // track after, e.g., tab switching.
     gBrowser.loadURIWithFlags(gBrowser.currentURI.spec,
                               nsIWebNavigation.LOAD_FLAGS_BYPASS_CLASSIFIER,
                               null, null, null);
 
@@ -4880,48 +4840,16 @@ var TabsProgressListener = {
         }
       } else if (aStateFlags & Ci.nsIWebProgressListener.STATE_STOP &&
                  aStatus == Cr.NS_BINDING_ABORTED &&
                  this._startedLoadTimer.has(aBrowser)) {
         this._startedLoadTimer.delete(aBrowser);
         TelemetryStopwatch.cancel("FX_PAGE_LOAD_MS", aBrowser);
       }
     }
-
-    // Attach a listener to watch for "click" events bubbling up from error
-    // pages and other similar pages (like about:newtab). This lets us fix bugs
-    // like 401575 which require error page UI to do privileged things, without
-    // letting error pages have any privilege themselves.
-    // We can't look for this during onLocationChange since at that point the
-    // document URI is not yet the about:-uri of the error page.
-
-    let isRemoteBrowser = aBrowser.isRemoteBrowser;
-    // We check isRemoteBrowser here to avoid requesting the doc CPOW
-    let doc = isRemoteBrowser ? null : aWebProgress.DOMWindow.document;
-
-    if (!isRemoteBrowser &&
-        aStateFlags & Ci.nsIWebProgressListener.STATE_STOP &&
-        Components.isSuccessCode(aStatus) &&
-        doc.documentURI.startsWith("about:") &&
-        !doc.documentURI.toLowerCase().startsWith("about:blank") &&
-        !doc.documentURI.toLowerCase().startsWith("about:home") &&
-        !doc.documentElement.hasAttribute("hasBrowserHandlers")) {
-      // STATE_STOP may be received twice for documents, thus store an
-      // attribute to ensure handling it just once.
-      doc.documentElement.setAttribute("hasBrowserHandlers", "true");
-      aBrowser.addEventListener("click", BrowserOnClick, true);
-      aBrowser.addEventListener("pagehide", function onPageHide(event) {
-        if (event.target.defaultView.frameElement)
-          return;
-        aBrowser.removeEventListener("click", BrowserOnClick, true);
-        aBrowser.removeEventListener("pagehide", onPageHide, true);
-        if (event.target.documentElement)
-          event.target.documentElement.removeAttribute("hasBrowserHandlers");
-      }, true);
-    }
   },
 
   onLocationChange(aBrowser, aWebProgress, aRequest, aLocationURI,
                              aFlags) {
     // Filter out location changes caused by anchor navigation
     // or history.push/pop/replaceState.
     if (aFlags & Ci.nsIWebProgressListener.LOCATION_CHANGE_SAME_DOCUMENT) {
       // Reader mode actually cares about these:

--- a/layout/base/tests/test_reftests_with_caret.html
+++ b/layout/base/tests/test_reftests_with_caret.html
@@ -61,16 +61,17 @@ const MAX_ITERATIONS = 1000;
 
 function createIframe(url,next) {
   var iframe = document.createElement("iframe");
   iframe.src = url;
   iframe.remotePageLoaded = remotePageLoaded;
   var me = this;
   var currentIteration = 0;
   function iframeLoadCompleted() {
+    iframe.focus();
     var docEl = iframe.contentDocument.documentElement;
     if (docEl.className.indexOf("reftest-wait") >= 0) {
       if (currentIteration++ > MAX_ITERATIONS) {
         ok(false, "iframe load for " + url + " timed out");
         endTest();
       } else {
         setTimeout(iframeLoadCompleted, 0);
       }
@@ -79,17 +80,16 @@ function createIframe(url,next) {
     iframe.remotePageLoaded(function() {
       if (next) {
         setTimeout(function(){createIframe(next,null);}, 0)
       }
     });
   }
   iframe.addEventListener("load", iframeLoadCompleted);
   window.document.body.appendChild(iframe);
-  iframe.focus();
 };
 
 function refTest(test,ref) {
   createIframe(test,ref);
 };
 
 var caretBlinkTime = null;
 function endTest() {

--- a/toolkit/components/aboutmemory/tests/test_aboutmemory4.xul
+++ b/toolkit/components/aboutmemory/tests/test_aboutmemory4.xul
@@ -32,52 +32,58 @@
 
   // Load the given file into the frame, then copy+paste the entire frame and
   // check that the cut text matches what we expect.
   function test(aFilename, aExpected, aNext) {
     let frame = document.createElementNS("http://www.w3.org/1999/xhtml", "iframe")
     frame.height = 300;
     frame.src = "about:memory?file=" + makePathname(aFilename);
     document.documentElement.appendChild(frame);
-    frame.focus();
+    frame.addEventListener("load", function onFrameLoad(e) {
+      if (frame.location && frame.location.href != "about:blank") {
+        return;
+      }
+      frame.removeEventListener("load", onFrameLoad);
+      frame.focus();
 
-    // Initialize the clipboard contents.
-    SpecialPowers.clipboardCopyString("initial clipboard value");
+      // Initialize the clipboard contents.
+      SpecialPowers.clipboardCopyString("initial clipboard value");
 
-    let numFailures = 0, maxFailures = 30;
+      let numFailures = 0, maxFailures = 30;
 
-    // Because the file load is async, we don't know when it will finish and
-    // the output will show up.  So we poll.
-    function copyPasteAndCheck() {
-      // Copy and paste frame contents, and filter out non-deterministic
-      // differences.
-      synthesizeKey("A", {accelKey: true});
-      synthesizeKey("C", {accelKey: true});
-      let actual = SpecialPowers.getClipboardData("text/unicode");
-      actual = actual.replace(/\(pid \d+\)/, "(pid NNN)");
+      // Because the file load is async, we don't know when it will finish and
+      // the output will show up.  So we poll.
+      function copyPasteAndCheck() {
+        // Copy and paste frame contents, and filter out non-deterministic
+        // differences.
+        synthesizeKey("A", {accelKey: true});
+        synthesizeKey("C", {accelKey: true});
+        let actual = SpecialPowers.getClipboardData("text/unicode");
+        actual = actual.replace(/\(pid \d+\)/, "(pid NNN)");
 
-      if (actual.trim() === aExpected.trim()) {
-        SimpleTest.ok(true, "Clipboard has the expected contents");
-        aNext();
-      } else {
-        numFailures++;
-        if (numFailures === maxFailures) {
-          ok(false, "pasted text doesn't match");
-          dump("******EXPECTED******\n");
-          dump(aExpected);
-          dump("*******ACTUAL*******\n");
-          dump(actual);
-          dump("********************\n");
-          SimpleTest.finish();
+        if (actual.trim() === aExpected.trim()) {
+          SimpleTest.ok(true, "Clipboard has the expected contents");
+          aNext();
         } else {
-          setTimeout(copyPasteAndCheck, 100);
+          numFailures++;
+          if (numFailures === maxFailures) {
+            ok(false, "pasted text doesn't match");
+            dump("******EXPECTED******\n");
+            dump(aExpected);
+            dump("*******ACTUAL*******\n");
+            dump(actual);
+            dump("********************\n");
+            SimpleTest.finish();
+          } else {
+            setTimeout(copyPasteAndCheck, 100);
+          }
         }
       }
-    }
-    copyPasteAndCheck();
+      copyPasteAndCheck();
+    });
   }
 
   // Returns a function that chains together multiple test() calls.
   function chain(aFrameIds) {
     let x = aFrameIds.shift();
     if (x) {
       return function() { test(x.filename, x.expected, chain(aFrameIds)); }
     } else {