--- a/modules/libjar/zipwriter/test/unit/head_zipwriter.js
+++ b/modules/libjar/zipwriter/test/unit/head_zipwriter.js
@@ -39,8 +39,18 @@ var ZipReader = Components.Constructor("
 
 var tmpDir = do_get_profile();
 var tmpFile = tmpDir.clone();
 tmpFile.append("zipwriter-test.zip");
 if (tmpFile.exists())
   tmpFile.remove(true);
 
 var zipW = new ZipWriter();
+
+do_register_cleanup(function() {
+  try {
+    zipW.close();
+  } catch (e) {
+    // Just ignore a failure here and attempt to delete the file anyway.
+  }
+  if (tmpFile.exists())
+    tmpFile.remove(true);
+});

deleted file mode 100644
--- a/modules/libjar/zipwriter/test/unit/tail_zipwriter.js
+++ /dev/null
@@ -1,14 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/.
- */
-
-try {
-  zipW.close();
-}
-catch (e) {
-  // Just ignore a failure here and attempt to delete the file anyway.
-}
-
-if (tmpFile.exists())
-  tmpFile.remove(true);

--- a/modules/libjar/zipwriter/test/unit/xpcshell.ini
+++ b/modules/libjar/zipwriter/test/unit/xpcshell.ini
@@ -1,11 +1,11 @@
 [DEFAULT]
 head = head_zipwriter.js
-tail = tail_zipwriter.js
+tail =
 support-files =
   data/test_bug446708/thumbs/st14-1.tiff
   data/emptyfile.txt
   data/smallfile.txt
   data/test.png
   data/test.txt
   data/test.zip
   data/test_bug399727.html

--- a/toolkit/components/url-classifier/tests/unit/head_urlclassifier.js
+++ b/toolkit/components/url-classifier/tests/unit/head_urlclassifier.js
@@ -472,8 +472,12 @@ function waitUntilMetaDataSaved(expected
       do_timeout(1000, waitUntilMetaDataSaved.bind(null, expectedState,
                                                          expectedChecksum,
                                                          callback));
     }
   });
 }
 
 cleanUp();
+
+do_register_cleanup(function() {
+  cleanUp();
+});

deleted file mode 100644
--- a/toolkit/components/url-classifier/tests/unit/tail_urlclassifier.js
+++ /dev/null
@@ -1,1 +0,0 @@
-cleanUp();

--- a/toolkit/components/url-classifier/tests/unit/xpcshell.ini
+++ b/toolkit/components/url-classifier/tests/unit/xpcshell.ini
@@ -1,11 +1,11 @@
 [DEFAULT]
 head = head_urlclassifier.js
-tail = tail_urlclassifier.js
+tail =
 skip-if = toolkit == 'android'
 support-files =
   data/digest1.chunk
   data/digest2.chunk
 
 [test_addsub.js]
 [test_bug1274685_unowned_list.js]
 [test_backoff.js]

--- a/toolkit/identity/tests/unit/head_identity.js
+++ b/toolkit/identity/tests/unit/head_identity.js
@@ -241,16 +241,20 @@ Services.prefs.setBoolPref("toolkit.iden
 
 // Switch on firefox accounts
 var initialPrefFXAValue = false;
 try {
   initialPrefFXAValue = Services.prefs.getBoolPref("identity.fxaccounts.enabled");
 } catch (noPref) {}
 Services.prefs.setBoolPref("identity.fxaccounts.enabled", true);
 
-// after execution, restore prefs
 do_register_cleanup(function() {
   log("restoring prefs to their initial values");
   Services.prefs.setBoolPref("toolkit.identity.debug", initialPrefDebugValue);
   Services.prefs.setBoolPref("identity.fxaccounts.enabled", initialPrefFXAValue);
+
+  // Pre-emptively shut down to clear resources.
+  if (typeof IdentityService !== "undefined") {
+    IdentityService.shutdown();
+  } else if (typeof IDService !== "undefined") {
+    IDService.shutdown();
+  }
 });
-
-

deleted file mode 100644
--- a/toolkit/identity/tests/unit/tail_identity.js
+++ /dev/null
@@ -1,8 +0,0 @@
-
-// pre-emptively shut down to clear resources
-if (typeof IdentityService !== "undefined") {
-  IdentityService.shutdown();
-} else if (typeof IDService !== "undefined") {
-  IDService.shutdown();
-}
-

--- a/toolkit/identity/tests/unit/xpcshell.ini
+++ b/toolkit/identity/tests/unit/xpcshell.ini
@@ -1,11 +1,11 @@
 [DEFAULT]
 head = head_identity.js
-tail = tail_identity.js
+tail =
 skip-if = (appname != "b2g" || toolkit == 'gonk')
 support-files =
   data/idp_1/.well-known/browserid
   data/idp_invalid_1/.well-known/browserid
 
 # Test load modules first so syntax failures are caught early.
 [test_load_modules.js]
 [test_minimalidentity.js]

--- a/uriloader/exthandler/tests/unit/head_handlerService.js
+++ b/uriloader/exthandler/tests/unit/head_handlerService.js
@@ -28,29 +28,29 @@ var HandlerServiceTest = {
       this.__consoleSvc = Cc["@mozilla.org/consoleservice;1"].
                           getService(Ci.nsIConsoleService);
     return this.__consoleSvc;
   },
 
 
   //**************************************************************************//
   // nsISupports
-  
+
   interfaces: [Ci.nsIDirectoryServiceProvider, Ci.nsISupports],
 
   QueryInterface: function HandlerServiceTest_QueryInterface(iid) {
     if (!this.interfaces.some( function(v) { return iid.equals(v) } ))
       throw Cr.NS_ERROR_NO_INTERFACE;
     return this;
   },
 
 
   //**************************************************************************//
   // Initialization & Destruction
-  
+
   init: function HandlerServiceTest_init() {
     // Register ourselves as a directory provider for the datasource file
     // if there isn't one registered already.
     try {
       this._dirSvc.get("UMimTyp", Ci.nsIFile);
     } catch (ex) {
       this._dirSvc.registerProvider(this);
       this._providerRegistered = true;
@@ -156,8 +156,12 @@ var HandlerServiceTest = {
     message = "*** HandlerServiceTest: " + message;
     this._consoleSvc.logStringMessage(message);
     print(message);
   }
 
 };
 
 HandlerServiceTest.init();
+
+do_register_cleanup(function() {
+  HandlerServiceTest.destroy();
+});

deleted file mode 100644
--- a/uriloader/exthandler/tests/unit/tail_handlerService.js
+++ /dev/null
@@ -1,5 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-HandlerServiceTest.destroy();

--- a/uriloader/exthandler/tests/unit/xpcshell.ini
+++ b/uriloader/exthandler/tests/unit/xpcshell.ini
@@ -1,11 +1,11 @@
 [DEFAULT]
 head = head_handlerService.js
-tail = tail_handlerService.js
+tail =
 run-sequentially = Bug 912235 - Intermittent failures
 
 [test_getTypeFromExtension_ext_to_type_mapping.js]
 [test_getTypeFromExtension_with_empty_Content_Type.js]
 [test_badMIMEType.js]
 [test_handlerService.js]
 support-files = mailcap
 # Bug 676997: test consistently fails on Android