--- a/browser/extensions/shumway/content/shumway.js
+++ b/browser/extensions/shumway/content/shumway.js
@@ -37087,17 +37087,17 @@ var BinaryFileReader = function binaryFi
             }
             complete(xhr.response);
           }
         };
         xhr.send(null);
       },
       readAsync: function (ondata, onerror, onopen, oncomplete, onhttpstatus) {
         var xhr = new XMLHttpRequest({
-            mozAnon: true, mozSystem: true
+            mozSystem: true
           });
         var url = this.url;
         xhr.open(this.method || 'GET', url, true);
         var isNotProgressive;
         try {
           xhr.responseType = 'moz-chunked-arraybuffer';
           isNotProgressive = xhr.responseType !== 'moz-chunked-arraybuffer';
         } catch (e) {

--- a/content/base/src/nsXMLHttpRequest.cpp
+++ b/content/base/src/nsXMLHttpRequest.cpp
@@ -378,17 +378,17 @@ nsXMLHttpRequest::InitParameters(bool aA
   // Check for permissions.
   nsCOMPtr<nsPIDOMWindow> window = do_QueryInterface(GetOwner());
   if (!window || !window->GetDocShell()) {
     return;
   }
 
   // Chrome is always allowed access, so do the permission check only
   // for non-chrome pages.
-  if (!IsSystemXHR() && aSystem) {
+  if (!IsSystemXHR()) {
     nsCOMPtr<nsIDocument> doc = window->GetExtantDoc();
     if (!doc) {
       return;
     }
 
     nsCOMPtr<nsIPrincipal> principal = doc->NodePrincipal();
     nsCOMPtr<nsIPermissionManager> permMgr =
       do_GetService(NS_PERMISSIONMANAGER_CONTRACTID);

--- a/content/base/src/nsXMLHttpRequest.h
+++ b/content/base/src/nsXMLHttpRequest.h
@@ -193,21 +193,16 @@ public:
     nsCOMPtr<nsIGlobalObject> global = do_QueryInterface(aGlobal.GetAsSupports());
     nsCOMPtr<nsIScriptObjectPrincipal> principal =
       do_QueryInterface(aGlobal.GetAsSupports());
     if (!global || ! principal) {
       aRv.Throw(NS_ERROR_FAILURE);
       return nullptr;
     }
 
-    if (!aParams.mMozAnon && aParams.mMozSystem) {
-      aRv.Throw(NS_ERROR_DOM_SECURITY_ERR);
-      return nullptr;
-    }
-
     nsRefPtr<nsXMLHttpRequest> req = new nsXMLHttpRequest();
     req->Construct(principal->GetPrincipal(), global);
     req->InitParameters(aParams.mMozAnon, aParams.mMozSystem);
     return req.forget();
   }
 
   static already_AddRefed<nsXMLHttpRequest>
   Constructor(const mozilla::dom::GlobalObject& aGlobal,

--- a/content/base/test/file_restrictedEventSource.sjs
+++ b/content/base/test/file_restrictedEventSource.sjs
@@ -1,16 +1,18 @@
 function handleRequest(request, response)
 {
   if ((request.queryString == "test=user1_xhr" &&
        request.hasHeader("Authorization") &&
        request.getHeader("Authorization") == "Basic dXNlciAxOnBhc3N3b3JkIDE=") ||
       (request.queryString == "test=user1_evtsrc" &&
        request.hasHeader("Authorization") &&
-       request.getHeader("Authorization") == "Basic dXNlciAxOnBhc3N3b3JkIDE=")) {
+       request.getHeader("Authorization") == "Basic dXNlciAxOnBhc3N3b3JkIDE=" &&
+       request.hasHeader("Cookie") &&
+       request.getHeader("Cookie") == "test=5c")) {
     response.setStatusLine(null, 200, "OK");
     response.setHeader("Content-Type", "text/event-stream", false);
     response.setHeader("Access-Control-Allow-Origin", "http://mochi.test:8888", false);
     response.setHeader("Access-Control-Allow-Credentials", "true", false);
     response.setHeader("Cache-Control", "no-cache, must-revalidate", false);
     if (request.queryString == "test=user1_xhr") {
       response.setHeader("Set-Cookie", "test=5c", false);
     }

--- a/content/base/test/mochitest.ini
+++ b/content/base/test/mochitest.ini
@@ -516,17 +516,16 @@ support-files =
 [test_bug869006.html]
 [test_bug876282.html]
 [test_bug890580.html]
 [test_bug894874.html]
 [test_bug895239.html]
 [test_bug895974.html]
 [test_bug902847.html]
 [test_bug907892.html]
-[test_bug927196.html]
 [test_caretPositionFromPoint.html]
 [test_classList.html]
 [test_copypaste.html]
 [test_copypaste.xhtml]
 [test_createHTMLDocument.html]
 [test_declare_stylesheet_obsolete.html]
 [test_domparser_null_char.html]
 [test_domparsing.html]

--- a/content/base/test/test_XHR_parameters.html
+++ b/content/base/test/test_XHR_parameters.html
@@ -48,21 +48,22 @@ function runTests() {
     try {
       xhr = new XMLHttpRequest(value);
     } catch (ex) {
       ok(false, "Got unexpected exception: " + ex);
       return;
     }
     ok(xhr instanceof XMLHttpRequest, "passed " + JSON.stringify(value));
 
-    // If the page doesnt have privileges to create a system XHR,
-    // this flag will always be false no matter what is passed.
-    let expectedAnon = Boolean(value && value.mozAnon);
+    // If the page doesnt have privileges to create a system or anon XHR,
+    // these flags will always be false no matter what is passed.
+    let expectedAnon = false;
     let expectedSystem = false;
     if (havePrivileges) {
+      expectedAnon = Boolean(value && value.mozAnon);
       expectedSystem = Boolean(value && value.mozSystem);
     }
     is(xhr.mozAnon, expectedAnon, "testing mozAnon");
     is(xhr.mozSystem, expectedSystem, "testing mozSystem");
   }
 
   function testInvalidParameter(value) {
     let expectedError;
@@ -78,20 +79,21 @@ function runTests() {
   }
 
   // Run the tests once without API privileges...
   validParameters.forEach(testValidParameter);
   invalidParameters.forEach(testInvalidParameter);
 
   // ...and once with privileges.
   havePrivileges = true;
-  SpecialPowers.pushPermissions([{'type': 'systemXHR', 'allow': true, 'context': document}], function() {
-    validParameters.forEach(testValidParameter);
-    invalidParameters.forEach(testInvalidParameter);
+  SpecialPowers.addPermission("systemXHR", true, document);
 
-    SimpleTest.finish();
-  });
+  validParameters.forEach(testValidParameter);
+  invalidParameters.forEach(testInvalidParameter);
+  SpecialPowers.removePermission("systemXHR", document);
+
+  SimpleTest.finish();
 }
 
 </script>
 </pre>
 </body>
 </html>

--- a/content/base/test/test_XHR_system.html
+++ b/content/base/test/test_XHR_system.html
@@ -21,17 +21,17 @@ const PROTECTED_URL = "file:///etc/passw
 const REDIRECT_URL = window.location.protocol + "//" + window.location.host + "/tests/content/base/test/file_XHR_system_redirect.html";
 const CROSSSITE_URL = "http://example.com/tests/content/base/test/test_XHR_system.html";
 
 tests.push(function test_cross_origin() {
   // System XHR can load cross-origin resources.
 
   is(window.location.hostname, "mochi.test", "correct origin");
 
-  let xhr = new XMLHttpRequest({mozAnon: true, mozSystem: true});
+  let xhr = new XMLHttpRequest({mozSystem: true});
   is(xhr.mozSystem, true, ".mozSystem == true");
   xhr.open("GET", CROSSSITE_URL);
   xhr.onload = function onload() {
     is(xhr.status, 200, "correct HTTP status");
     ok(xhr.responseText != null, "HTTP response non-null");
     ok(xhr.responseText.length, "HTTP response not empty");
     runNextTest();
   };
@@ -40,17 +40,17 @@ tests.push(function test_cross_origin() 
     runNextTest();
   }
   xhr.send();
 });
 
 tests.push(function test_file_uri() {
   // System XHR is not permitted to access file:/// URIs.
 
-  let xhr = new XMLHttpRequest({mozAnon: true, mozSystem: true});
+  let xhr = new XMLHttpRequest({mozSystem: true});
   is(xhr.mozSystem, true, ".mozSystem == true");
   xhr.open("GET", PROTECTED_URL);
   let error;
   try {
     xhr.send();
   } catch (ex) {
     error = ex;
   }
@@ -59,17 +59,17 @@ tests.push(function test_file_uri() {
   is(error.message, "Access to restricted URI denied");
 
   runNextTest();
 });
 
 tests.push(function test_redirect_to_file_uri() {
   // System XHR won't load file:/// URIs even if an HTTP resource redirects there.
 
-  let xhr = new XMLHttpRequest({mozAnon: true, mozSystem: true});
+  let xhr = new XMLHttpRequest({mozSystem: true});
   is(xhr.mozSystem, true, ".mozSystem == true");
   xhr.open("GET", REDIRECT_URL);
   xhr.onload = function onload() {
     ok(false, "Should not have loaded");
     runNextTest();
   };
   xhr.onerror = function onerror(event) {
     ok(true, "Got an error event: " + event);

--- a/content/base/test/test_bug338583.html
+++ b/content/base/test/test_bug338583.html
@@ -459,18 +459,18 @@ https://bugzilla.mozilla.org/show_bug.cg
       ok(gEventSourceObj5_b.hits['fn_onmessage'] == 0, "Test 5.b failed");
       gEventSourceObj5_b.close();
       setTestHasFinished(test_id);
     }, parseInt(3000*stress_factor));
   }
 
   function doTest5_c(test_id)
   {
-    // credentials using the auth cache
-    var xhr = new XMLHttpRequest({mozAnon: true, mozSystem: true});
+    // credentials using the auth cache and cookies
+    var xhr = new XMLHttpRequest({mozAnon: false, mozSystem: true});
     xhr.withCredentials = true;
     // also, test mixed mode UI
     xhr.open("GET", "https://example.com/tests/content/base/test/file_restrictedEventSource.sjs?test=user1_xhr", true, "user 1", "password 1");
     xhr.send();
     xhr.onloadend = function() {
       ok(xhr.status == 200, "Failed to set credentials in test 5.c");
 
       gEventSourceObj5_c = new EventSource("https://example.com/tests/content/base/test/file_restrictedEventSource.sjs?test=user1_evtsrc",
@@ -489,17 +489,17 @@ https://bugzilla.mozilla.org/show_bug.cg
         gEventSourceObj5_c.close();
         doTest5_d(test_id);
       }, parseInt(3000*stress_factor));
     };
   }
 
   function doTest5_d(test_id)
   {
-    var xhr = new XMLHttpRequest({mozAnon: true, mozSystem: true});
+    var xhr = new XMLHttpRequest({mozAnon: false, mozSystem: true});
     xhr.withCredentials = true;
     xhr.open("GET", "https://example.com/tests/content/base/test/file_restrictedEventSource.sjs?test=user2_xhr", true, "user 2", "password 2");
     xhr.send();
     xhr.onloadend = function() {
       ok(xhr.status == 200, "Failed to set credentials in test 5.d");
   
       gEventSourceObj5_d = new EventSource("https://example.com/tests/content/base/test/file_restrictedEventSource.sjs?test=user2_evtsrc");
       ok(!gEventSourceObj5_d.withCredentials, "Wrong withCredentials in test 5.d");
@@ -516,18 +516,18 @@ https://bugzilla.mozilla.org/show_bug.cg
         gEventSourceObj5_d.close();
         setTestHasFinished(test_id);
       }, parseInt(3000*stress_factor));
     };
   }
 
   function doTest5_e(test_id)
   {
-    // credentials using the auth cache
-    var xhr = new XMLHttpRequest({mozAnon: true, mozSystem: true});
+    // credentials using the auth cache and cookies
+    var xhr = new XMLHttpRequest({mozAnon: false, mozSystem: true});
     xhr.withCredentials = true;
     xhr.open("GET", "http://example.org/tests/content/base/test/file_restrictedEventSource.sjs?test=user1_xhr", true, "user 1", "password 1");
     xhr.send();
     xhr.onloadend = function() {
       ok(xhr.status == 200, "Failed to set credentials in test 5.e");
 
       gEventSourceObj5_e = new EventSource("http://example.org/tests/content/base/test/file_restrictedEventSource.sjs?test=user1_evtsrc",
                                            { get withCredentials() { return true; } } );
@@ -545,17 +545,17 @@ https://bugzilla.mozilla.org/show_bug.cg
         gEventSourceObj5_e.close();
         doTest5_f(test_id);
       }, parseInt(5000*stress_factor));
     };
   }
 
   function doTest5_f(test_id)
   {
-    var xhr = new XMLHttpRequest({mozAnon: true, mozSystem: true});
+    var xhr = new XMLHttpRequest({mozAnon: false, mozSystem: true});
     xhr.withCredentials = true;
     xhr.open("GET", "http://example.org/tests/content/base/test/file_restrictedEventSource.sjs?test=user2_xhr", true, "user 2", "password 2");
     xhr.send();
     xhr.onloadend = function() {
       ok(xhr.status == 200, "Failed to set credentials in test 5.f");
 
       gEventSourceObj5_f = new EventSource("http://example.org/tests/content/base/test/file_restrictedEventSource.sjs?test=user2_evtsrc",
                                            { });

--- a/content/base/test/test_bug426308.html
+++ b/content/base/test/test_bug426308.html
@@ -17,17 +17,17 @@ https://bugzilla.mozilla.org/show_bug.cg
 <pre id="test">
 <script class="testbody" type="text/javascript">
 
 /** Test for Bug 426308 **/
 
 const SJS_URL = "http://example.org:80/tests/content/base/test/bug426308-redirect.sjs";
 
 function startTest() {
-  var req = new XMLHttpRequest({mozAnon: true, mozSystem: true});
+  var req = new XMLHttpRequest({mozAnon: false, mozSystem: true});
   req.open("GET", SJS_URL + "?" + window.location.href, false);
   req.send(null);
 
   is(req.status, 200, "Redirect did not happen");
 
   SimpleTest.finish();
 }
 

--- a/content/base/test/test_bug431701.html
+++ b/content/base/test/test_bug431701.html
@@ -46,17 +46,17 @@ function frameDoc(id) {
 
 function createDoc() {
   return document.implementation.createDocument('', 'html', null);
 }
 
 function xhrDoc(idx) {
   return function() {
     // Defy same-origin restrictions!
-    var xhr = new XMLHttpRequest({mozAnon: true, mozSystem: true});
+    var xhr = new XMLHttpRequest({mozAnon: false, mozSystem: true});
     xhr.open("GET", docSources[idx], false);
     xhr.send();
     return xhr.responseXML;
   };
 }
 
 // Each row has the document getter function, then the characterSet,
 // inputEncoding expected for that document.

--- a/content/base/test/test_bug804395.html
+++ b/content/base/test/test_bug804395.html
@@ -14,41 +14,41 @@ https://bugzilla.mozilla.org/show_bug.cg
 <p id="display"></p>
 <div id="content" style="display: none">
 
 </div>
 <pre id="test">
 <script type="application/javascript">
 
 function test200() {
-  var xhr = new XMLHttpRequest({mozAnon: true, mozSystem: true});
+  var xhr = new XMLHttpRequest({mozAnon: false, mozSystem: true});
   xhr.open('GET', 'jar:http://example.org/tests/content/base/test/file_bug804395.jar!/foo.bar', true);
   xhr.onreadystatechange = function() {
     if (xhr.readyState == 4) {
       ok(xhr.status == 200, "Existing file must have Status 200!");
       runTests();
     }
   }
   xhr.send(null);
 }
 
 function test404() {
-  var xhr = new XMLHttpRequest({mozAnon: true, mozSystem: true});
+  var xhr = new XMLHttpRequest({mozAnon: false, mozSystem: true});
   xhr.open('GET', 'jar:http://example.org/tests/content/base/test/file_bug804395.jar!/foo.do_not_exist', true);
   xhr.onreadystatechange = function() {
     if (xhr.readyState == 4) {
       ok(xhr.status == 404, "Non existing file must have Status 404!");
       runTests();
     }
   }
   xhr.send(null);
 }
 
 function test0() {
-  var xhr = new XMLHttpRequest({mozAnon: true, mozSystem: true});
+  var xhr = new XMLHttpRequest({mozAnon: false, mozSystem: true});
   xhr.open('GET', 'jar:http://example.org/tests/content/base/test/file_bug804395.jar!/foo.bar', true);
   ok(xhr.status == 0, "Not Sent request must have status 0");
   runTests();
 }
 
 var tests = [ test200, test404, test0 ];
 function runTests() {
   if (!tests.length) {

deleted file mode 100644
--- a/content/base/test/test_bug927196.html
+++ /dev/null
@@ -1,64 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<!--
-https://bugzilla.mozilla.org/show_bug.cgi?id=426308
--->
-<head>
-  <title>Test for Bug 426308</title>
-  <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
-  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
-</head>
-<body>
-<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=927196">Mozilla Bug 927196</a>
-<p id="display"></p>
-<div id="content" style="display: none">
-  
-</div>
-<pre id="test">
-<script class="testbody" type="text/javascript">
-
-/** Test for Bug 927196 **/
-
-function startTest() {
-  try {
-    req = new XMLHttpRequest({mozSystem: true});
-    ok(false, "Should not be reached");
-  } catch(e) {
-    is(e.name, "SecurityError", "XMLHttpRequest should not be mozSystem");
-  }
-
-  req = new XMLHttpRequest({mozAnon: true});
-  is(req.mozAnon, true, "XMLHttpRequest should be mozAnon");
-  is(req.mozSystem, false, "XMLHttpRequest should not be mozSystem");
-
-  req = new XMLHttpRequest({mozAnon: true, mozSystem: true});
-  is(req.mozAnon, true, "XMLHttpRequest should be mozAnon");
-  is(req.mozSystem, true, "XMLHttpRequest should be mozSystem");
-
-  try {
-    req = new XMLHttpRequest({mozAnon: false, mozSystem: true});
-    ok(false, "Should not be reached");
-  } catch(e) {
-    is(e.name, "SecurityError", "XMLHttpRequest should throw SecurityError");
-  }
-
-  SimpleTest.finish();
-}
-
-SimpleTest.waitForExplicitFinish();
-
-var req = new XMLHttpRequest({mozAnon: true});
-is(req.mozAnon, true, "XMLHttpRequest should be mozAnon");
-is(req.mozSystem, false, "XMLHttpRequest should not be mozSystem");
-
-req = new XMLHttpRequest({mozAnon: true, mozSystem: true});
-is(req.mozAnon, false, "XMLHttpRequest should be mozAnon");
-is(req.mozSystem, false, "XMLHttpRequest should not be mozSystem");
-
-addLoadEvent(function() {
-   SpecialPowers.pushPermissions([{'type': 'systemXHR', 'allow': true, 'context': document}], startTest);
-});
-</script>
-</pre>
-</body>
-</html>

--- a/content/base/test/test_xhr_forbidden_headers.html
+++ b/content/base/test/test_xhr_forbidden_headers.html
@@ -65,17 +65,17 @@ function  startTest() {
       value = channel.getRequestHeader(headers[i]);
     }
     catch(e) {}
 
     isnot(value, "test" + i, "Setting " + headers[i] + " header in unprivileged context");
   }
 
   // Try setting headers in privileged context
-  request = new XMLHttpRequest({mozAnon: true, mozSystem: true});
+  request = new XMLHttpRequest({mozAnon: false, mozSystem: true});
   request.open("GET", window.location.href);
   for (i = 0; i < headers.length; i++)
     request.setRequestHeader(headers[i], "test" + i);
 
   // Read out headers
   var channel = SpecialPowers.wrap(request).channel.QueryInterface(SpecialPowers.Ci.nsIHttpChannel);
   for (i = 0; i < headers.length; i++) {
     var value = channel.getRequestHeader(headers[i]);

--- a/dom/permission/tests/test_systemXHR.html
+++ b/dom/permission/tests/test_systemXHR.html
@@ -12,17 +12,17 @@ https://bugzilla.mozilla.org/show_bug.cg
 <body>
 <a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=815105">Mozilla Bug 815105 </a>
 <p id="display"></p>
 <div id="content" style="display: none"></div>
 <pre id="test">
 <script type="application/javascript;version=1.8" src="file_framework.js"></script>
 <script type="application/javascript;version=1.8">
 function verifier(success, failure) {
-  var xhr = new XMLHttpRequest({mozAnon: true, mozSystem: true});
+  var xhr = new XMLHttpRequest({mozSystem: true});
   if (xhr.mozSystem === true) {
     success("systemXHR");
   } else {
     failure("Couldn't create systemXHR");
   }
 }
 
 var gData = [

--- a/dom/workers/XMLHttpRequest.cpp
+++ b/dom/workers/XMLHttpRequest.cpp
@@ -1494,21 +1494,16 @@ already_AddRefed<XMLHttpRequest>
 XMLHttpRequest::Constructor(const GlobalObject& aGlobal,
                             const MozXMLHttpRequestParameters& aParams,
                             ErrorResult& aRv)
 {
   JSContext* cx = aGlobal.GetContext();
   WorkerPrivate* workerPrivate = GetWorkerPrivateFromContext(cx);
   MOZ_ASSERT(workerPrivate);
 
-  if (!aParams.mMozAnon && aParams.mMozSystem) {
-    aRv.Throw(NS_ERROR_DOM_SECURITY_ERR);
-    return nullptr;
-  }
-
   nsRefPtr<XMLHttpRequest> xhr = new XMLHttpRequest(workerPrivate);
 
   if (workerPrivate->XHRParamsAllowed()) {
     xhr->mMozAnon = aParams.mMozAnon;
     xhr->mMozSystem = aParams.mMozSystem;
   }
 
   return xhr.forget();

--- a/dom/workers/test/test_xhr_system.html
+++ b/dom/workers/test/test_xhr_system.html
@@ -21,32 +21,34 @@ function message(event) {
   else if(event.data.test == 'is')
     is(event.data.a, event.data.b, event.data.event);
   else if(event.data.test == 'finish') {
     run();
   }
 };
 
 function test1() {
+  // ...and once with privileges.
+  SpecialPowers.addPermission("systemXHR", true, document);
   var worker = new Worker("test_xhr_system.js");
   worker.onmessage = message;
   worker.postMessage(true);
 }
 
 var tests = [ test1 ];
 function run() {
   if (!tests.length) {
+    SpecialPowers.removePermission("systemXHR", document);
     SimpleTest.finish();
     return;
   }
 
   var func = tests.shift();
   func();
 }
 
 SimpleTest.waitForExplicitFinish();
-
-SpecialPowers.pushPermissions([{'type': 'systemXHR', 'allow': true, 'context': document}], run);
+run();
 
 </script>
 </pre>
 </body>
 </html>

--- a/dom/workers/test/test_xhr_system.js
+++ b/dom/workers/test/test_xhr_system.js
@@ -6,19 +6,19 @@ function is(a, b, msg) {
   postMessage({ event: msg, test: 'is', a: a, b: b });
 }
 
 self.onmessage = function onmessage(event) {
 
   // An XHR with system privileges will be able to do cross-site calls.
 
   const TEST_URL = "http://example.com/tests/content/base/test/test_XHR_system.html";
-  is(location.hostname, "mochi.test", "hostname should be mochi.test");
+  is(location.hostname, "mochi.test", "hostname");
 
-  var xhr = new XMLHttpRequest({mozAnon: true, mozSystem: true});
+  var xhr = new XMLHttpRequest({mozSystem: true});
   is(xhr.mozSystem, true, ".mozSystem == true");
   xhr.open("GET", TEST_URL);
   xhr.onload = function onload() {
     is(xhr.status, 200);
     ok(xhr.responseText != null);
     ok(xhr.responseText.length);
     postMessage({test: "finish"});
   };

--- a/testing/mochitest/manifest.webapp
+++ b/testing/mochitest/manifest.webapp
@@ -22,16 +22,17 @@
     "camera":{},
     "geolocation":{},
     "wifi-manage":{},
     "wifi":{},
     "desktop-notification":{},
     "idle":{},
     "network-events":{},
     "embed-apps":{},
+    "systemXHR":{},
     "audio-channel-content":{},
     "audio-channel-alarm":{}
   },
   "locales": {
     "en-US": {
       "name": "Mochitest",
       "description": "Mochitests"
     }