diff -r 000000000000 -r 6474c204b198 browser/base/content/test/plugins/browser_bug744745.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/base/content/test/plugins/browser_bug744745.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,43 @@
+/* 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/. */
+
+var gTestBrowser = null;
+var gNumPluginBindingsAttached = 0;
+
+Components.utils.import("resource://gre/modules/Services.jsm");
+
+function test() {
+  waitForExplicitFinish();
+  registerCleanupFunction(function() {
+    Services.prefs.clearUserPref("plugins.click_to_play");
+    gTestBrowser.removeEventListener("PluginBindingAttached", pluginBindingAttached, true, true);
+    gBrowser.removeCurrentTab();
+    window.focus();
+  });
+
+  Services.prefs.setBoolPref("plugins.click_to_play", true);
+  setTestPluginEnabledState(Ci.nsIPluginTag.STATE_CLICKTOPLAY);
+
+  gBrowser.selectedTab = gBrowser.addTab();
+  gTestBrowser = gBrowser.selectedBrowser;
+  gTestBrowser.addEventListener("PluginBindingAttached", pluginBindingAttached, true, true);
+  var gHttpTestRoot = getRootDirectory(gTestPath).replace("chrome://mochitests/content/", "http://127.0.0.1:8888/");
+  gTestBrowser.contentWindow.location = gHttpTestRoot + "plugin_bug744745.html";
+}
+
+function pluginBindingAttached() {
+  gNumPluginBindingsAttached++;
+
+  if (gNumPluginBindingsAttached == 1) {
+    var doc = gTestBrowser.contentDocument;
+    var testplugin = doc.getElementById("test");
+    ok(testplugin, "should have test plugin");
+    var style = getComputedStyle(testplugin);
+    ok('opacity' in style, "style should have opacity set");
+    is(style.opacity, 1, "opacity should be 1");
+    finish();
+  } else {
+    ok(false, "if we've gotten here, something is quite wrong");
+  }
+}