--- a/toolkit/mozapps/extensions/addonManager.js
+++ b/toolkit/mozapps/extensions/addonManager.js
@@ -65,26 +65,26 @@ amManager.prototype = {
 
       case "message-manager-close":
       case "message-manager-disconnect":
         this.childClosed(aSubject);
         break;
     }
   },
 
-  async installAddonFromWebpage(aMimetype, aBrowser, aInstallingPrincipal,
-                                    aUri, aHash, aName, aIcon, aCallback) {
+  installAddonFromWebpage(aMimetype, aBrowser, aInstallingPrincipal,
+                          aUri, aHash, aName, aIcon, aCallback) {
     let retval = true;
     if (!AddonManager.isInstallAllowed(aMimetype, aInstallingPrincipal)) {
       aCallback = null;
       retval = false;
     }
 
-    let aInstall = await AddonManager.getInstallForURL(aUri, null, aMimetype, aHash, aName, aIcon, null, aBrowser);
-    function callCallback(uri, status) {
+    AddonManager.getInstallForURL(aUri, null, aMimetype, aHash, aName, aIcon, null, aBrowser).then(aInstall => {
+      function callCallback(uri, status) {
         try {
           aCallback.onInstallEnded(uri, status);
         } catch (e) {
           Cu.reportError(e);
         }
       }
 
       if (!aInstall) {
@@ -111,16 +111,17 @@ amManager.prototype = {
 
           onInstallEnded(aInstall, aStatus) {
             callCallback(aUri, SUCCESS);
           }
         });
       }
 
       AddonManager.installAddonFromWebpage(aMimetype, aBrowser, aInstallingPrincipal, aInstall);
+    });
 
     return retval;
   },
 
   notify(aTimer) {
     AddonManagerPrivate.backgroundUpdateTimerHandler();
   },
 

--- a/toolkit/mozapps/extensions/test/browser/browser.ini
+++ b/toolkit/mozapps/extensions/test/browser/browser.ini
@@ -46,17 +46,16 @@ skip-if = buildapp == 'mulet'
 [browser_bug577990.js]
 [browser_bug580298.js]
 [browser_bug586574.js]
 [browser_bug587970.js]
 [browser_bug591465.js]
 skip-if = os == "linux" && !debug # Bug 1395539 - fails on multi-core
 [browser_bug591663.js]
 [browser_bug596336.js]
-[browser_bug616841.js]
 [browser_bug618502.js]
 [browser_bug679604.js]
 [browser_bug590347.js]
 [browser_checkAddonCompatibility.js]
 [browser_details.js]
 [browser_discovery.js]
 [browser_dragdrop.js]
 skip-if = buildapp == 'mulet'

deleted file mode 100644
--- a/toolkit/mozapps/extensions/test/browser/browser_bug616841.js
+++ /dev/null
@@ -1,20 +0,0 @@
-/* Any copyright is dedicated to the Public Domain.
- * http://creativecommons.org/publicdomain/zero/1.0/
- */
-
-function test_string_compare() {
-  ok("C".localeCompare("D") < 0, "C < D");
-  ok("D".localeCompare("C") > 0, "D > C");
-  ok("\u010C".localeCompare("D") < 0, "\u010C < D");
-  ok("D".localeCompare("\u010C") > 0, "D > \u010C");
-}
-
-async function test() {
-  waitForExplicitFinish();
-
-  test_string_compare();
-
-  let aAddon = await AddonManager.getAddonByID("foo");
-  test_string_compare();
-  finish();
-}

--- a/toolkit/mozapps/extensions/test/xpcshell/test_startup.js
+++ b/toolkit/mozapps/extensions/test/xpcshell/test_startup.js
@@ -138,23 +138,21 @@ async function run_test() {
   check_startup_changes(AddonManager.STARTUP_CHANGE_UNINSTALLED, []);
   check_startup_changes(AddonManager.STARTUP_CHANGE_DISABLED, []);
   check_startup_changes(AddonManager.STARTUP_CHANGE_ENABLED, []);
 
   Assert.ok(!gExtensionsJSON.exists());
 
   Assert.ok(!gAddonStartup.exists());
 
-  let [a1, a2, a3, a4, a5, a6, a7] = await AddonManager.getAddonsByIDs(["addon1@tests.mozilla.org",
-                                                                        "addon2@tests.mozilla.org",
-                                                                        "addon3@tests.mozilla.org",
-                                                                        "addon4@tests.mozilla.org",
-                                                                        "addon5@tests.mozilla.org",
-                                                                        "addon6@tests.mozilla.org",
-                                                                        "addon7@tests.mozilla.org"]);
+  let [a1, a2, a3, a4, a5] = await AddonManager.getAddonsByIDs(["addon1@tests.mozilla.org",
+                                                                "addon2@tests.mozilla.org",
+                                                                "addon3@tests.mozilla.org",
+                                                                "addon4@tests.mozilla.org",
+                                                                "addon5@tests.mozilla.org"]);
   Assert.equal(a1, null);
   do_check_not_in_crash_annotation(addon1.id, addon1.version);
   Assert.equal(a2, null);
   do_check_not_in_crash_annotation(addon2.id, addon2.version);
   Assert.equal(a3, null);
   do_check_not_in_crash_annotation(addon3.id, addon3.version);
   Assert.equal(a4, null);
   Assert.equal(a5, null);
@@ -423,21 +421,18 @@ async function run_test_4() {
 
   check_startup_changes(AddonManager.STARTUP_CHANGE_INSTALLED, []);
   check_startup_changes(AddonManager.STARTUP_CHANGE_CHANGED, ["addon2@tests.mozilla.org"]);
   check_startup_changes(AddonManager.STARTUP_CHANGE_UNINSTALLED, ["addon1@tests.mozilla.org"]);
   check_startup_changes(AddonManager.STARTUP_CHANGE_DISABLED, []);
   check_startup_changes(AddonManager.STARTUP_CHANGE_ENABLED, []);
   Assert.ok(gCachePurged);
 
-  let [a1, a2, a3, a4, a5] = await AddonManager.getAddonsByIDs(["addon1@tests.mozilla.org",
-                                                                "addon2@tests.mozilla.org",
-                                                                "addon3@tests.mozilla.org",
-                                                                "addon4@tests.mozilla.org",
-                                                                "addon5@tests.mozilla.org"]);
+  let [a1, a2] = await AddonManager.getAddonsByIDs(["addon1@tests.mozilla.org",
+                                                    "addon2@tests.mozilla.org"]);
   Assert.equal(a1, null);
   Assert.ok(!isExtensionInBootstrappedList(profileDir, "addon1@tests.mozilla.org"));
   Assert.ok(!isExtensionInBootstrappedList(userDir, "addon1@tests.mozilla.org"));
 
   Assert.notEqual(a2, null);
   Assert.equal(a2.id, "addon2@tests.mozilla.org");
   Assert.equal(a2.version, "2.2");
   Assert.ok(!isExtensionInBootstrappedList(profileDir, a2.id));
@@ -460,21 +455,18 @@ async function run_test_5() {
 
   check_startup_changes(AddonManager.STARTUP_CHANGE_INSTALLED, ["addon1@tests.mozilla.org"]);
   check_startup_changes(AddonManager.STARTUP_CHANGE_CHANGED, ["addon2@tests.mozilla.org"]);
   check_startup_changes(AddonManager.STARTUP_CHANGE_UNINSTALLED, []);
   check_startup_changes(AddonManager.STARTUP_CHANGE_DISABLED, []);
   check_startup_changes(AddonManager.STARTUP_CHANGE_ENABLED, []);
   Assert.ok(gCachePurged);
 
-  let [a1, a2, a3, a4, a5] = await AddonManager.getAddonsByIDs(["addon1@tests.mozilla.org",
-                                                                "addon2@tests.mozilla.org",
-                                                                "addon3@tests.mozilla.org",
-                                                                "addon4@tests.mozilla.org",
-                                                                "addon5@tests.mozilla.org"]);
+  let [a1, a2] = await AddonManager.getAddonsByIDs(["addon1@tests.mozilla.org",
+                                                    "addon2@tests.mozilla.org"]);
   Assert.notEqual(a1, null);
   Assert.equal(a1.id, "addon1@tests.mozilla.org");
   Assert.equal(a1.version, "1.1");
   Assert.ok(!isExtensionInBootstrappedList(profileDir, a1.id));
   Assert.ok(isExtensionInBootstrappedList(userDir, a1.id));
   Assert.ok(!hasFlag(a1.permissions, AddonManager.PERM_CAN_UNINSTALL));
   Assert.ok(!hasFlag(a1.permissions, AddonManager.PERM_CAN_UPGRADE));
   do_check_in_crash_annotation(addon1.id, a1.version);
@@ -503,21 +495,18 @@ async function run_test_6() {
 
   check_startup_changes(AddonManager.STARTUP_CHANGE_INSTALLED, []);
   check_startup_changes(AddonManager.STARTUP_CHANGE_CHANGED, []);
   check_startup_changes(AddonManager.STARTUP_CHANGE_UNINSTALLED, []);
   check_startup_changes(AddonManager.STARTUP_CHANGE_DISABLED, []);
   check_startup_changes(AddonManager.STARTUP_CHANGE_ENABLED, []);
   Assert.ok(gCachePurged);
 
-  let [a1, a2, a3, a4, a5] = await AddonManager.getAddonsByIDs(["addon1@tests.mozilla.org",
-                                                                "addon2@tests.mozilla.org",
-                                                                "addon3@tests.mozilla.org",
-                                                                "addon4@tests.mozilla.org",
-                                                                "addon5@tests.mozilla.org"]);
+  let [a1, a2] = await AddonManager.getAddonsByIDs(["addon1@tests.mozilla.org",
+                                                    "addon2@tests.mozilla.org"]);
   Assert.notEqual(a1, null);
   Assert.equal(a1.id, "addon1@tests.mozilla.org");
   Assert.equal(a1.version, "1.1");
   Assert.ok(!isExtensionInBootstrappedList(profileDir, a1.id));
   Assert.ok(isExtensionInBootstrappedList(userDir, a1.id));
   Assert.ok(!hasFlag(a1.permissions, AddonManager.PERM_CAN_UNINSTALL));
   Assert.ok(!hasFlag(a1.permissions, AddonManager.PERM_CAN_UPGRADE));
   do_check_in_crash_annotation(addon1.id, a1.version);
@@ -605,21 +594,18 @@ async function run_test_8() {
 
   check_startup_changes(AddonManager.STARTUP_CHANGE_INSTALLED, []);
   check_startup_changes(AddonManager.STARTUP_CHANGE_CHANGED, []);
   check_startup_changes(AddonManager.STARTUP_CHANGE_UNINSTALLED, ["addon2@tests.mozilla.org"]);
   check_startup_changes(AddonManager.STARTUP_CHANGE_DISABLED, []);
   check_startup_changes(AddonManager.STARTUP_CHANGE_ENABLED, []);
   Assert.ok(gCachePurged);
 
-  let [a1, a2, a3, a4, a5] = await AddonManager.getAddonsByIDs(["addon1@tests.mozilla.org",
-                                                                "addon2@tests.mozilla.org",
-                                                                "addon3@tests.mozilla.org",
-                                                                "addon4@tests.mozilla.org",
-                                                                "addon5@tests.mozilla.org"]);
+  let [a1, a2] = await AddonManager.getAddonsByIDs(["addon1@tests.mozilla.org",
+                                                    "addon2@tests.mozilla.org"]);
   Assert.notEqual(a1, null);
   Assert.equal(a1.id, "addon1@tests.mozilla.org");
   Assert.equal(a1.version, "1.2");
   Assert.ok(isExtensionInBootstrappedList(profileDir, a1.id));
   Assert.ok(!isExtensionInBootstrappedList(userDir, a1.id));
   Assert.ok(hasFlag(a1.permissions, AddonManager.PERM_CAN_UNINSTALL));
   Assert.ok(hasFlag(a1.permissions, AddonManager.PERM_CAN_UPGRADE));
   do_check_in_crash_annotation(addon1.id, a1.version);
@@ -811,21 +797,19 @@ async function run_test_12() {
   shutdownManager();
 
   writeInstallRDFForExtension(addon1, profileDir);
   writeInstallRDFForExtension(addon2, userDir);
   writeInstallRDFForExtension(addon3, globalDir);
 
   startupManager(false);
 
-  let [a1, a2, a3, a4, a5] = await AddonManager.getAddonsByIDs(["addon1@tests.mozilla.org",
-                                                                "addon2@tests.mozilla.org",
-                                                                "addon3@tests.mozilla.org",
-                                                                "addon4@tests.mozilla.org",
-                                                                "addon5@tests.mozilla.org"]);
+  let [a1, a2, a3] = await AddonManager.getAddonsByIDs(["addon1@tests.mozilla.org",
+                                                        "addon2@tests.mozilla.org",
+                                                        "addon3@tests.mozilla.org"]);
   Assert.notEqual(a1, null);
   Assert.ok(!a1.userDisabled);
   Assert.ok(a1.seen);
   Assert.ok(a1.isActive);
 
   Assert.notEqual(a2, null);
   Assert.ok(a2.userDisabled);
   Assert.ok(!a2.seen);
@@ -854,21 +838,19 @@ async function run_test_12() {
   Services.prefs.setIntPref("extensions.autoDisableScopes", AddonManager.SCOPE_SYSTEM);
 
   writeInstallRDFForExtension(addon1, profileDir);
   writeInstallRDFForExtension(addon2, userDir);
   writeInstallRDFForExtension(addon3, globalDir);
 
   startupManager(false);
 
-  let [a1_2, a2_2, a3_2, a4_2, a5_2] = await AddonManager.getAddonsByIDs(["addon1@tests.mozilla.org",
-                                                                          "addon2@tests.mozilla.org",
-                                                                          "addon3@tests.mozilla.org",
-                                                                          "addon4@tests.mozilla.org",
-                                                                          "addon5@tests.mozilla.org"]);
+  let [a1_2, a2_2, a3_2] = await AddonManager.getAddonsByIDs(["addon1@tests.mozilla.org",
+                                                              "addon2@tests.mozilla.org",
+                                                              "addon3@tests.mozilla.org"]);
   Assert.notEqual(a1_2, null);
   Assert.ok(!a1_2.userDisabled);
   Assert.ok(a1_2.seen);
   Assert.ok(a1_2.isActive);
 
   Assert.notEqual(a2_2, null);
   Assert.ok(!a2_2.userDisabled);
   Assert.ok(a2_2.seen);
@@ -897,21 +879,19 @@ async function run_test_12() {
   Services.prefs.setIntPref("extensions.autoDisableScopes", AddonManager.SCOPE_USER + AddonManager.SCOPE_SYSTEM);
 
   writeInstallRDFForExtension(addon1, profileDir);
   writeInstallRDFForExtension(addon2, userDir);
   writeInstallRDFForExtension(addon3, globalDir);
 
   startupManager(false);
 
-  let [a1_3, a2_3, a3_3, a4_3, a5_3] = await AddonManager.getAddonsByIDs(["addon1@tests.mozilla.org",
-                                                                          "addon2@tests.mozilla.org",
-                                                                          "addon3@tests.mozilla.org",
-                                                                          "addon4@tests.mozilla.org",
-                                                                          "addon5@tests.mozilla.org"]);
+  let [a1_3, a2_3, a3_3] = await AddonManager.getAddonsByIDs(["addon1@tests.mozilla.org",
+                                                              "addon2@tests.mozilla.org",
+                                                              "addon3@tests.mozilla.org"]);
   Assert.notEqual(a1_3, null);
   Assert.ok(!a1_3.userDisabled);
   Assert.ok(a1_3.seen);
   Assert.ok(a1_3.isActive);
 
   Assert.notEqual(a2_3, null);
   Assert.ok(a2_3.userDisabled);
   Assert.ok(!a2_3.seen);