--- a/netwerk/protocol/app/AppProtocolHandler.js
+++ b/netwerk/protocol/app/AppProtocolHandler.js
@@ -2,17 +2,16 @@
  * 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/. */
 
 "use strict";
 
 const Cc = Components.classes;
 const Ci = Components.interfaces;
 const Cu = Components.utils;
-const Cr = Components.results;
 
 Cu.import("resource://gre/modules/XPCOMUtils.jsm");
 Cu.import("resource://gre/modules/Services.jsm");
 
 XPCOMUtils.defineLazyServiceGetter(this, "appsService",
                                    "@mozilla.org/AppsService;1",
                                    "nsIAppsService");
 
@@ -48,32 +47,29 @@ AppProtocolHandler.prototype = {
     uri.init(Ci.nsIStandardURL.URLTYPE_STANDARD, -1, aSpec, aOriginCharset,
              aBaseURI);
     return uri.QueryInterface(Ci.nsIURI);
   },
 
   newChannel: function app_phNewChannel(aURI) {
     // We map app://ABCDEF/path/to/file.ext to
     // jar:file:///path/to/profile/webapps/ABCDEF/application.zip!/path/to/file.ext
-    let url = aURI.QueryInterface(Ci.nsIURL);
-    let appId = aURI.host;
-    let fileSpec = url.filePath;
+    let noScheme = aURI.spec.substring(6);
+    let firstSlash = noScheme.indexOf("/");
+
+    let appId = noScheme;
+    let fileSpec = aURI.path;
+
+    if (firstSlash) {
+      appId = noScheme.substring(0, firstSlash);
+    }
 
     // Build a jar channel and masquerade as an app:// URI.
     let appInfo = this.getAppInfo(appId);
     let uri;
-
-    if (!appInfo) {
-      // That should not happen, so dump() inconditionnally.
-      // We create a dummy channel instead of throwing to let the
-      // downstream user get a 404 error.
-      dump("!! got no appInfo for " + appId + "\n");
-      return new DummyChannel();
-    }
-
     if (this._runningInParent || appInfo.isCoreApp) {
       // In-parent and CoreApps can directly access files, so use jar:file://
       uri = "jar:file://" + appInfo.basePath + appId + "/application.zip!" + fileSpec;
     } else {
       // non-CoreApps in child need to ask parent for file handle, use jar:ipcfile://
       uri = "jar:remoteopenfile://" + appInfo.basePath + appId + "/application.zip!" + fileSpec;
     }
     let channel = Services.io.newChannel(uri, null, null);
@@ -83,117 +79,9 @@ AppProtocolHandler.prototype = {
     return channel;
   },
 
   allowPort: function app_phAllowPort(aPort, aScheme) {
     return false;
   }
 };
 
-/**
-  * This dummy channel implementation only provides enough functionality
-  * to return a fake 404 error when the caller asks for an app:// URL
-  * containing an unknown appId.
-  */
-function DummyChannel() {
-}
-
-DummyChannel.prototype = {
-  QueryInterface: XPCOMUtils.generateQI([Ci.nsIRequest,
-                                         Ci.nsIChannel,
-                                         Ci.nsIJARChannel]),
-
-  // nsIRequest
-  name: "dummy_app_channel",
-
-  isPending: function dc_isPending() {
-    return this._pending;
-  },
-
-  status: Cr.NS_ERROR_FILE_NOT_FOUND,
-
-  cancel: function dc_cancel() {
-  },
-
-  suspend: function dc_suspend() {
-    this._suspendCount++;
-  },
-
-  resume: function dc_resume() {
-    if (this._suspendCount <= 0)
-      throw Cr.NS_ERROR_UNEXPECTED;
-
-    if (--this._suspendCount == 0 && this._pending) {
-      this._dispatch();
-    }
-  },
-
-  loadGroup: null,
-  loadFlags: Ci.nsIRequest.LOAD_NORMAL,
-
-  // nsIChannel
-  originalURI: Services.io.newURI("app://unknown/nothing.html", null, null),
-  URI: Services.io.newURI("app://unknown/nothing.html", null, null),
-
-  owner: null,
-  notificationCallbacks: null,
-  securityInfo: null,
-  contentType: null,
-  contentCharset: null,
-  contentLength: 0,
-  contentDisposition: Ci.nsIChannel.DISPOSITION_INLINE,
-  contentDispositionFilename: "",
-
-  _pending: false,
-  _suspendCount: 0,
-  _listener: null,
-  _context: null,
-
-  open: function dc_open() {
-    return Cr.NS_ERROR_NOT_IMPLEMENTED;
-  },
-
-  _dispatch: function dc_dispatch() {
-    let request = this;
-
-    Services.tm.currentThread.dispatch(
-    {
-      run: function dc_run() {
-        request._listener.onStartRequest(request, request._context);
-        request._listener.onStopRequest(request, request._context,
-                                        Cr.NS_ERROR_FILE_NOT_FOUND);
-        if (request.loadGroup) {
-          request.loadGroup.removeRequest(request, request._context,
-                                          Cr.NS_ERROR_FILE_NOT_FOUND);
-        }
-        request._pending = false;
-        request.notificationCallbacks = null;
-        request._listener = null;
-        request._context = null;
-      }
-    },
-    Ci.nsIThread.DISPATCH_NORMAL);
-  },
-
-  asyncOpen: function dc_asyncopenfunction(aListener, aContext) {
-    if (this.loadGroup) {
-      this.loadGroup.addRequest(this, aContext);
-    }
-
-    this._listener = aListener;
-    this._context = aContext;
-    this._pending = true;
-
-    if (!this._suspended) {
-      this._dispatch();
-    }
-  },
-
-  // nsIJarChannel, needed for XHR to turn NS_ERROR_FILE_NOT_FOUND into
-  // a 404 error.
-  isUnsafe: false,
-
-  setAppURI: function(aURI) {
-    throw Cr.NS_ERROR_NOT_IMPLEMENTED;
-  }
-};
-
 this.NSGetFactory = XPCOMUtils.generateNSGetFactory([AppProtocolHandler]);