diff -r 000000000000 -r 6474c204b198 browser/devtools/commandline/test/head.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/devtools/commandline/test/head.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,36 @@
+/* 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/. */
+
+const TEST_BASE_HTTP = "http://example.com/browser/browser/devtools/commandline/test/";
+const TEST_BASE_HTTPS = "https://example.com/browser/browser/devtools/commandline/test/";
+
+// Import the GCLI test helper
+let testDir = gTestPath.substr(0, gTestPath.lastIndexOf("/"));
+Services.scriptloader.loadSubScript(testDir + "/helpers.js", this);
+Services.scriptloader.loadSubScript(testDir + "/mockCommands.js", this);
+
+gDevTools.testing = true;
+SimpleTest.registerCleanupFunction(() => {
+  gDevTools.testing = false;
+});
+
+function whenDelayedStartupFinished(aWindow, aCallback) {
+  Services.obs.addObserver(function observer(aSubject, aTopic) {
+    if (aWindow == aSubject) {
+      Services.obs.removeObserver(observer, aTopic);
+      executeSoon(aCallback);
+    }
+  }, "browser-delayed-startup-finished", false);
+}
+
+/**
+ * Force GC on shutdown, because it seems that GCLI can outrun the garbage
+ * collector in some situations, which causes test failures in later tests
+ * Bug 774619 is an example.
+ */
+registerCleanupFunction(function tearDown() {
+  window.QueryInterface(Ci.nsIInterfaceRequestor)
+      .getInterface(Ci.nsIDOMWindowUtils)
+      .garbageCollect();
+});