--- a/netwerk/test/httpserver/test/head_utils.js
+++ b/netwerk/test/httpserver/test/head_utils.js
@@ -72,17 +72,17 @@ function fileContents(file)
  * without the trailing line separator.
  *
  * @param data : string
  *   a string consisting of lines of data separated by CRLFs
  * @returns Iterator
  *   an Iterator which returns each line from data in turn; note that this
  *   includes a final empty line if data ended with a CRLF
  */
-function LineIterator(data)
+function* LineIterator(data)
 {
   var start = 0, index = 0;
   do
   {
     index = data.indexOf("\r\n");
     if (index >= 0)
       yield data.substring(0, index);
     else
@@ -102,17 +102,17 @@ function LineIterator(data)
  * @param expectedLines : [string]
  *   an array of the expected lines of text
  * @throws string
  *   an error message if iter doesn't agree with expectedLines
  */
 function expectLines(iter, expectedLines)
 {
   var index = 0;
-  for (var line in iter)
+  for (var line of iter)
   {
     if (expectedLines.length == index)
       throw "Error: got more than " + expectedLines.length + " expected lines!";
 
     var expected = expectedLines[index++];
     if (expected !== line)
       throw "Error on line " + index + "!\n" +
             "  actual: '" + line + "',\n" +
@@ -150,19 +150,19 @@ function writeDetails(request, response)
  * point the body of the response will be returned next from the iterator.
  *
  * @param iter : Iterator
  *   an iterator over the CRLF-delimited lines in an HTTP response, currently
  *   just after the Request-Line
  */
 function skipHeaders(iter)
 {
-  var line = iter.next();
+  var line = iter.next().value;
   while (line !== "")
-    line = iter.next();
+    line = iter.next().value;
 }
 
 /**
  * Checks that the exception e (which may be an XPConnect-created exception
  * object or a raw nsresult number) is the given nsresult.
  *
  * @param e : Exception or nsresult
  *   the actual exception

--- a/netwerk/test/httpserver/test/test_host.js
+++ b/netwerk/test/httpserver/test/test_host.js
@@ -262,17 +262,17 @@ function checkPrimariesThrow(id)
 /**
  * Utility function to check for a 400 response.
  */
 function check400(data)
 {
   var iter = LineIterator(data);
 
   // Status-Line
-  var firstLine = iter.next();
+  var { value: firstLine } = iter.next();
   do_check_eq(firstLine.substring(0, HTTP_400_LEADER_LENGTH), HTTP_400_LEADER);
 }
 
 
 /***************
  * BEGIN TESTS *
  ***************/
 
@@ -291,17 +291,17 @@ function http10Request(request, response
 }
 data = "GET /http/1.0-request HTTP/1.0\r\n" +
        "\r\n";
 function check10(data)
 {
   var iter = LineIterator(data);
 
   // Status-Line
-  do_check_eq(iter.next(), "HTTP/1.0 200 TEST PASSED");
+  do_check_eq(iter.next().value, "HTTP/1.0 200 TEST PASSED");
 
   skipHeaders(iter);
 
   // Okay, next line must be the data we expected to be written
   var body =
     [
      "Method:  GET",
      "Path:    /http/1.0-request",
@@ -390,17 +390,17 @@ function http11goodHost(request, respons
 data = "GET /http/1.1-good-host HTTP/1.1\r\n" +
        "Host: localhost:4444\r\n" +
        "\r\n";
 function check11goodHost(data)
 {
   var iter = LineIterator(data);
 
   // Status-Line
-  do_check_eq(iter.next(), "HTTP/1.1 200 TEST PASSED");
+  do_check_eq(iter.next().value, "HTTP/1.1 200 TEST PASSED");
 
   skipHeaders(iter);
 
   // Okay, next line must be the data we expected to be written
   var body =
     [
      "Method:  GET",
      "Path:    /http/1.1-good-host",
@@ -427,17 +427,17 @@ function http11ipHost(request, response)
 data = "GET /http/1.1-ip-host HTTP/1.1\r\n" +
        "Host: 127.0.0.1:4444\r\n" +
        "\r\n";
 function check11ipHost(data)
 {
   var iter = LineIterator(data);
 
   // Status-Line
-  do_check_eq(iter.next(), "HTTP/1.1 200 TEST PASSED");
+  do_check_eq(iter.next().value, "HTTP/1.1 200 TEST PASSED");
 
   skipHeaders(iter);
 
   // Okay, next line must be the data we expected to be written
   var body =
     [
      "Method:  GET",
      "Path:    /http/1.1-ip-host",
@@ -512,17 +512,17 @@ tests.push(test);
 data = "GET /http/1.0-request HTTP/1.0\r\n" +
        "Host: not-localhost:4444\r\n" +
        "\r\n";
 function check10ip(data)
 {
   var iter = LineIterator(data);
 
   // Status-Line
-  do_check_eq(iter.next(), "HTTP/1.0 200 TEST PASSED");
+  do_check_eq(iter.next().value, "HTTP/1.0 200 TEST PASSED");
 
   skipHeaders(iter);
 
   // Okay, next line must be the data we expected to be written
   var body =
     [
      "Method:  GET",
      "Path:    /http/1.0-request",
@@ -549,17 +549,17 @@ function http11goodHostWackyPort(request
 data = "GET /http/1.1-good-host-wacky-port HTTP/1.1\r\n" +
        "Host: localhost\r\n" +
        "\r\n";
 function check11goodHostWackyPort(data)
 {
   var iter = LineIterator(data);
 
   // Status-Line
-  do_check_eq(iter.next(), "HTTP/1.1 200 TEST PASSED");
+  do_check_eq(iter.next().value, "HTTP/1.1 200 TEST PASSED");
 
   skipHeaders(iter);
 
   // Okay, next line must be the data we expected to be written
   var body =
     [
      "Method:  GET",
      "Path:    /http/1.1-good-host-wacky-port",

--- a/netwerk/test/httpserver/test/test_request_line_split_in_two_packets.js
+++ b/netwerk/test/httpserver/test/test_request_line_split_in_two_packets.js
@@ -60,17 +60,17 @@ for (var i = 0; i < str.length; i += 163
 function checkVeryLongRequestLine(data)
 {
   var iter = LineIterator(data);
 
   print("data length: " + data.length);
   print("iter object: " + iter);
 
   // Status-Line
-  do_check_eq(iter.next(), "HTTP/1.1 200 TEST PASSED");
+  do_check_eq(iter.next().value, "HTTP/1.1 200 TEST PASSED");
 
   skipHeaders(iter);
 
   // Okay, next line must be the data we expected to be written
   var body =
     [
      "Method:  GET",
      "Path:    /very-long-request-line",
@@ -107,17 +107,17 @@ for (var i = 0; i < str.length; i += 100
 function checkLotsOfLeadingBlankLines(data)
 {
   var iter = LineIterator(data);
 
   // Status-Line
   print("data length: " + data.length);
   print("iter object: " + iter);
 
-  do_check_eq(iter.next(), "HTTP/1.1 200 TEST PASSED");
+  do_check_eq(iter.next().value, "HTTP/1.1 200 TEST PASSED");
 
   skipHeaders(iter);
 
   // Okay, next line must be the data we expected to be written
   var body =
     [
      "Method:  GET",
      "Path:    /lots-of-leading-blank-lines",

--- a/netwerk/test/httpserver/test/test_seizepower.js
+++ b/netwerk/test/httpserver/test/test_seizepower.js
@@ -152,17 +152,17 @@ function checkRawData(data)
 {
   do_check_eq(data, "Raw data!");
 }
 
 var data1 = "GET /called-too-late HTTP/1.0\r\n" +
        "\r\n";
 function checkTooLate(data)
 {
-  do_check_eq(LineIterator(data).next(), "too-late passed");
+  do_check_eq(LineIterator(data).next().value, "too-late passed");
 }
 
 var data2 = "GET /exceptions HTTP/1.0\r\n" +
        "\r\n";
 function checkExceptions(data)
 {
   do_check_eq("exceptions test passed", data);
 }
@@ -173,10 +173,10 @@ function checkAsyncSeizure(data)
 {
   do_check_eq(data, "async seizure passed");
 }
 
 var data4 = "GET /seize-after-async HTTP/1.0\r\n" +
        "\r\n";
 function checkSeizeAfterAsync(data)
 {
-  do_check_eq(LineIterator(data).next(), "HTTP/1.0 200 async seizure pass");
+  do_check_eq(LineIterator(data).next().value, "HTTP/1.0 200 async seizure pass");
 }

--- a/netwerk/test/unit/test_backgroundfilesaver.js
+++ b/netwerk/test/unit/test_backgroundfilesaver.js
@@ -257,17 +257,17 @@ add_task(function test_setup()
   // Wait 10 minutes, that is half of the external xpcshell timeout.
   do_timeout(10 * 60 * 1000, function() {
     if (gStillRunning) {
       do_throw("Test timed out.");
     }
   })
 });
 
-add_task(function test_normal()
+add_task(function* test_normal()
 {
   // This test demonstrates the most basic use case.
   let destFile = getTempFile(TEST_FILE_NAME_1);
 
   // Create the object implementing the output stream.
   let saver = new BackgroundFileSaverOutputStream();
 
   // Set up callbacks for completion and target file name change.
@@ -291,17 +291,17 @@ add_task(function test_normal()
   // Only after we receive the completion notification, we can also be sure that
   // we've received the target file name change notification before it.
   do_check_true(receivedOnTargetChange);
 
   // Clean up.
   destFile.remove(false);
 });
 
-add_task(function test_combinations()
+add_task(function* test_combinations()
 {
   let initialFile = getTempFile(TEST_FILE_NAME_1);
   let renamedFile = getTempFile(TEST_FILE_NAME_2);
 
   // Keep track of the current file.
   let currentFile = null;
   function onTargetChange(aTarget) {
     currentFile = null;
@@ -398,17 +398,17 @@ add_task(function test_combinations()
         renamedFile.remove(false);
       }
     }
 
     do_print("Test case completed in " + (Date.now() - startTime) + " ms.");
   }
 });
 
-add_task(function test_setTarget_after_close_stream()
+add_task(function* test_setTarget_after_close_stream()
 {
   // This test checks the case where we close the output stream before we call
   // the setTarget method.  All the data should be buffered and written anyway.
   let destFile = getTempFile(TEST_FILE_NAME_1);
 
   // Test the case where the file does not already exists first, then the case
   // where the file already exists.
   for (let i = 0; i < 2; i++) {
@@ -432,17 +432,17 @@ add_task(function test_setTarget_after_c
     do_check_eq(EXPECTED_HASHES[TEST_DATA_SHORT.length],
                 toHex(saver.sha256Hash));
   }
 
   // Clean up.
   destFile.remove(false);
 });
 
-add_task(function test_setTarget_fast()
+add_task(function* test_setTarget_fast()
 {
   // This test checks a fast rename of the target file.
   let destFile1 = getTempFile(TEST_FILE_NAME_1);
   let destFile2 = getTempFile(TEST_FILE_NAME_2);
   let saver = new BackgroundFileSaverOutputStream();
   let completionPromise = promiseSaverComplete(saver);
 
   // Set the initial name after the stream is closed, then rename immediately.
@@ -455,17 +455,17 @@ add_task(function test_setTarget_fast()
   yield completionPromise;
 
   // Verify results and clean up.
   do_check_false(destFile1.exists());
   yield promiseVerifyContents(destFile2, TEST_DATA_SHORT);
   destFile2.remove(false);
 });
 
-add_task(function test_setTarget_multiple()
+add_task(function* test_setTarget_multiple()
 {
   // This test checks multiple renames of the target file.
   let destFile = getTempFile(TEST_FILE_NAME_1);
   let saver = new BackgroundFileSaverOutputStream();
   let completionPromise = promiseSaverComplete(saver);
 
   // Rename both before and after the stream is closed.
   saver.setTarget(getTempFile(TEST_FILE_NAME_2), false);
@@ -480,17 +480,17 @@ add_task(function test_setTarget_multipl
 
   // Verify results and clean up.
   do_check_false(getTempFile(TEST_FILE_NAME_2).exists());
   do_check_false(getTempFile(TEST_FILE_NAME_3).exists());
   yield promiseVerifyContents(destFile, TEST_DATA_SHORT);
   destFile.remove(false);
 });
 
-add_task(function test_enableAppend()
+add_task(function* test_enableAppend()
 {
   // This test checks append mode with hashing disabled.
   let destFile = getTempFile(TEST_FILE_NAME_1);
 
   // Test the case where the file does not already exists first, then the case
   // where the file already exists.
   for (let i = 0; i < 2; i++) {
     let saver = new BackgroundFileSaverOutputStream();
@@ -508,17 +508,17 @@ add_task(function test_enableAppend()
                                    : TEST_DATA_LONG + TEST_DATA_LONG);
     yield promiseVerifyContents(destFile, expectedContents);
   }
 
   // Clean up.
   destFile.remove(false);
 });
 
-add_task(function test_enableAppend_setTarget_fast()
+add_task(function* test_enableAppend_setTarget_fast()
 {
   // This test checks a fast rename of the target file in append mode.
   let destFile1 = getTempFile(TEST_FILE_NAME_1);
   let destFile2 = getTempFile(TEST_FILE_NAME_2);
 
   // Test the case where the file does not already exists first, then the case
   // where the file already exists.
   for (let i = 0; i < 2; i++) {
@@ -545,17 +545,17 @@ add_task(function test_enableAppend_setT
                                    : TEST_DATA_SHORT + TEST_DATA_SHORT);
     yield promiseVerifyContents(secondFile, expectedContents);
   }
 
   // Clean up.
   destFile1.remove(false);
 });
 
-add_task(function test_enableAppend_hash()
+add_task(function* test_enableAppend_hash()
 {
   // This test checks append mode, also verifying that the computed hash
   // includes the contents of the existing data.
   let destFile = getTempFile(TEST_FILE_NAME_1);
 
   // Test the case where the file does not already exists first, then the case
   // where the file already exists.
   for (let i = 0; i < 2; i++) {
@@ -577,30 +577,30 @@ add_task(function test_enableAppend_hash
     do_check_eq(EXPECTED_HASHES[expectedContents.length],
                 toHex(saver.sha256Hash));
   }
 
   // Clean up.
   destFile.remove(false);
 });
 
-add_task(function test_finish_only()
+add_task(function* test_finish_only()
 {
   // This test checks creating the object and doing nothing.
   let destFile = getTempFile(TEST_FILE_NAME_1);
   let saver = new BackgroundFileSaverOutputStream();
   function onTargetChange(aTarget) {
     do_throw("Should not receive the onTargetChange notification.");
   }
   let completionPromise = promiseSaverComplete(saver, onTargetChange);
   saver.finish(Cr.NS_OK);
   yield completionPromise;
 });
 
-add_task(function test_empty()
+add_task(function* test_empty()
 {
   // This test checks we still create an empty file when no data is fed.
   let destFile = getTempFile(TEST_FILE_NAME_1);
 
   let saver = new BackgroundFileSaverOutputStream();
   let completionPromise = promiseSaverComplete(saver);
 
   saver.setTarget(destFile, false);
@@ -612,17 +612,17 @@ add_task(function test_empty()
   // Verify results.
   do_check_true(destFile.exists());
   do_check_eq(destFile.fileSize, 0);
 
   // Clean up.
   destFile.remove(false);
 });
 
-add_task(function test_empty_hash()
+add_task(function* test_empty_hash()
 {
   // This test checks the hash of an empty file, both in normal and append mode.
   let destFile = getTempFile(TEST_FILE_NAME_1);
 
   // Test normal mode first, then append mode.
   for (let i = 0; i < 2; i++) {
     let saver = new BackgroundFileSaverOutputStream();
     if (i == 1) {
@@ -641,17 +641,17 @@ add_task(function test_empty_hash()
     do_check_eq(destFile.fileSize, 0);
     do_check_eq(EXPECTED_HASHES[0], toHex(saver.sha256Hash));
   }
 
   // Clean up.
   destFile.remove(false);
 });
 
-add_task(function test_invalid_hash()
+add_task(function* test_invalid_hash()
 {
   let saver = new BackgroundFileSaverStreamListener();
   let completionPromise = promiseSaverComplete(saver);
   // We shouldn't be able to get the hash if hashing hasn't been enabled
   try {
     let hash = saver.sha256Hash;
     do_throw("Shouldn't be able to get hash if hashing not enabled");
   } catch (ex if ex.result == Cr.NS_ERROR_NOT_AVAILABLE) { }
@@ -671,17 +671,17 @@ add_task(function test_invalid_hash()
   // Wait for completion so that the worker thread finishes dealing with the
   // target file. We expect it to fail.
   try {
     yield completionPromise;
     do_throw("completionPromise should throw");
   } catch (ex if ex.result == Cr.NS_ERROR_FAILURE) { }
 });
 
-add_task(function test_signature()
+add_task(function* test_signature()
 {
   // Check that we get a signature if the saver is finished.
   let destFile = getTempFile(TEST_FILE_NAME_1);
 
   let saver = new BackgroundFileSaverOutputStream();
   let completionPromise = promiseSaverComplete(saver);
 
   try {
@@ -699,17 +699,17 @@ add_task(function test_signature()
 
   // signatureInfo is an empty nsIArray
   do_check_eq(0, saver.signatureInfo.length);
 
   // Clean up.
   destFile.remove(false);
 });
 
-add_task(function test_signature_not_enabled()
+add_task(function* test_signature_not_enabled()
 {
   // Check that we get a signature if the saver is finished on Windows.
   let destFile = getTempFile(TEST_FILE_NAME_1);
 
   let saver = new BackgroundFileSaverOutputStream();
   let completionPromise = promiseSaverComplete(saver);
   saver.setTarget(destFile, false);
   yield promiseCopyToSaver(TEST_DATA_SHORT, saver, true);

--- a/netwerk/test/unit/test_bug826063.js
+++ b/netwerk/test/unit/test_bug826063.js
@@ -20,17 +20,17 @@ function LoadContext(usePrivateBrowsing)
   this.usePrivateBrowsing = usePrivateBrowsing;
 }
 LoadContext.prototype = {
   originAttributes: {},
   QueryInterface: XPCOMUtils.generateQI([Ci.nsILoadContext, Ci.nsIInterfaceRequestor]),
   getInterface: XPCOMUtils.generateQI([Ci.nsILoadContext])
 };
 
-function getChannels() {
+function* getChannels() {
   for (let u of URIs) {
     yield NetUtil.newChannel({
       uri: u,
       loadUsingSystemPrincipal: true
     });
   }
 }
 

--- a/netwerk/test/unit/test_cache_jar.js
+++ b/netwerk/test/unit/test_cache_jar.js
@@ -42,85 +42,80 @@ var thirdTests = [
   [0, false, 0, 0], [0, true, 0, 0], [1, false, 0, 1], [1, true, 0, 1],
   [0, false, 1, 0], [0, true, 1, 0], [1, false, 1, 0], [1, true, 1, 0]
 ];
 var fourthTests = [
   [0, false, 0, 0], [0, true, 0, 0], [1, false, 0, 0], [1, true, 0, 0],
   [0, false, 1, 1], [0, true, 1, 0], [1, false, 1, 0], [1, true, 1, 0]
 ];
 
-function run_all_tests() {
+async function run_all_tests() {
   for (let test of firstTests) {
     handlers_called = 0;
-    var chan = makeChan(URL, test[0], test[1], test[2]);
-    chan.asyncOpen2(new ChannelListener(doneFirstLoad, test[3]));
-    yield undefined;
+    await test_channel(...test);
   }
 
   // We can't easily cause webapp data to be cleared from the child process, so skip
   // the rest of these tests.
   let procType = Cc["@mozilla.org/xre/runtime;1"].getService(Ci.nsIXULRuntime).processType;
   if (procType != Ci.nsIXULRuntime.PROCESS_TYPE_DEFAULT)
     return;
 
   let attrs_inBrowser = JSON.stringify({ appId:1, inIsolatedMozBrowser:true });
   let attrs_notInBrowser = JSON.stringify({ appId:1 });
 
   Services.obs.notifyObservers(null, "clear-origin-attributes-data", attrs_inBrowser);
 
   for (let test of secondTests) {
     handlers_called = 0;
-    var chan = makeChan(URL, test[0], test[1], test[2]);
-    chan.asyncOpen2(new ChannelListener(doneFirstLoad, test[3]));
-    yield undefined;
+    await test_channel(...test);
   }
 
   Services.obs.notifyObservers(null, "clear-origin-attributes-data", attrs_notInBrowser);
   Services.obs.notifyObservers(null, "clear-origin-attributes-data", attrs_inBrowser);
 
   for (let test of thirdTests) {
     handlers_called = 0;
-    var chan = makeChan(URL, test[0], test[1], test[2]);
-    chan.asyncOpen2(new ChannelListener(doneFirstLoad, test[3]));
-    yield undefined;
+    await test_channel(...test);
   }
 
   let attrs_userContextId = JSON.stringify({ userContextId: 1 });
   Services.obs.notifyObservers(null, "clear-origin-attributes-data", attrs_userContextId);
 
   for (let test of fourthTests) {
     handlers_called = 0;
-    var chan = makeChan(URL, test[0], test[1], test[2]);
-    chan.asyncOpen2(new ChannelListener(doneFirstLoad, test[3]));
-    yield undefined;
+    await test_channel(...test);
   }
 }
 
-var gTests;
 function run_test() {
   do_get_profile();
   if (!newCacheBackEndUsed()) {
     do_check_true(true, "This test checks only cache2 specific behavior.");
     return;
   }
   do_test_pending();
   httpserv = new HttpServer();
   httpserv.registerPathHandler("/cached", cached_handler);
   httpserv.start(-1);
-  gTests = run_all_tests();
-  gTests.next();
+  run_all_tests().then(() => {
+    do_test_finished();
+  });
 }
 
-function doneFirstLoad(req, buffer, expected) {
+function test_channel(appId, inIsolatedMozBrowser, userContextId, expected) {
+  return new Promise(resolve => {
+    var chan = makeChan(URL, appId, inIsolatedMozBrowser, userContextId);
+    chan.asyncOpen2(new ChannelListener(doneFirstLoad.bind(null, resolve), expected));
+  });
+}
+
+function doneFirstLoad(resolve, req, buffer, expected) {
   // Load it again, make sure it hits the cache
   var oa = req.loadInfo.originAttributes;
   var chan = makeChan(URL, oa.appId, oa.isInIsolatedMozBrowserElement, oa.userContextId);
-  chan.asyncOpen2(new ChannelListener(doneSecondLoad, expected));
+  chan.asyncOpen2(new ChannelListener(doneSecondLoad.bind(null, resolve), expected));
 }
 
-function doneSecondLoad(req, buffer, expected) {
+function doneSecondLoad(resolve, req, buffer, expected) {
   do_check_eq(handlers_called, expected);
-  try {
-    gTests.next();
-  } catch (x) {
-    do_test_finished();
-  }
+  resolve();
 }