--- a/testing/marionette/listener.js
+++ b/testing/marionette/listener.js
@@ -32,18 +32,16 @@ Cu.import("chrome://marionette/content/s
 Cu.import("resource://gre/modules/FileUtils.jsm");
 Cu.import("resource://gre/modules/Task.jsm");
 Cu.import("resource://gre/modules/XPCOMUtils.jsm");
 
 Cu.importGlobalProperties(["URL"]);
 
 var contentLog = new logging.ContentLogger();
 
-var isB2G = false;
-
 var marionetteTestName;
 var winUtil = content.QueryInterface(Ci.nsIInterfaceRequestor)
     .getInterface(Ci.nsIDOMWindowUtils);
 var listenerId = null; // unique ID of this listener
 var curContainer = { frame: content, shadowRoot: null };
 var isRemoteBrowser = () => curContainer.frame.contentWindow !== null;
 var previousContainer = null;
 
@@ -643,19 +641,17 @@ function deleteSession(msg) {
   removeMessageListenerId("Marionette:sleepSession", sleepSession);
   removeMessageListenerId("Marionette:getAppCacheStatus", getAppCacheStatus);
   removeMessageListenerId("Marionette:setTestName", setTestName);
   removeMessageListenerId("Marionette:takeScreenshot", takeScreenshotFn);
   removeMessageListenerId("Marionette:addCookie", addCookieFn);
   removeMessageListenerId("Marionette:getCookies", getCookiesFn);
   removeMessageListenerId("Marionette:deleteAllCookies", deleteAllCookiesFn);
   removeMessageListenerId("Marionette:deleteCookie", deleteCookieFn);
-  if (isB2G) {
-    content.removeEventListener("mozbrowsershowmodalprompt", modalHandler);
-  }
+
   seenEls.clear();
   // reset container frame to the top-most frame
   curContainer = { frame: content, shadowRoot: null };
   curContainer.frame.focus();
   legacyactions.touchIds = {};
   if (action.inputStateMap !== undefined) {
     action.inputStateMap.clear();
   }