Remove nossl hack, as it isn't needed.

dart/site/try/app.yaml

 # Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 # App Engine configuration, see:
 # https://developers.google.com/appengine/docs/python/config/appconfig
 
 # The version number should be something like rSVN_REVISION.
 version: remember to edit app.yaml before deploying
 # This version name is used to create a new host, for example,
@@ skipping 84 matching lines @@
 - url: /favicon\.ico
   static_files: favicon.ico
   upload: favicon\.ico
   secure: always
 
 - url: /
   static_files: index.html
   upload: index.html
   secure: always
 
-# The nossl file below help work around bugs/features in interaction between
-# AppEngine and AppCache. When a return user goes to http://try.dartlang.org/
-# (no SSL), AppCache will serve index.html from cache, try to fetch the old
-# manifest (nossl.appcache) and the files listed in the manifest. In additation
-# the files listed in the manifest, it will also fetch index.html, as it is the
-# master. However, we want index.html to be redirected to the SSL version, and
-# AppCache sees this redirection as a network error. When an error occurs,
-# AppCache will keep serving the old page. So we configure nossl.appcache to
-# provide fallbacks for index.html and leap.dart.js. The fallback for
-# leap.dart.js is nossl.js which will take care of redirecting to
-# https://try.dartlang.org/ (with SSL) using JavaScript.  Unfortunately, Chrome
-# seems to keep the old version of index.html cached indefinitely. The only way
-# to avoid that appears to serve up a different index.html depending on if it
-# is a secure connection or not. This would require a Python script, and
-# something we may consider implementing in the future.
-- url: /nossl.appcache
-  static_files: nossl.appcache
-  upload: nossl.appcache
-  secure: optional
-
-- url: /nossl.js
-  static_files: nossl.js
-  upload: nossl.js
-  secure: optional
-
-- url: /nossl.html
-  static_files: nossl.html
-  upload: nossl.html
-  secure: optional
-
 - url: /ssl.appcache
   static_files: ssl.appcache
   upload: ssl.appcache
   secure: always
 
 - url: /(.*\.(html|js|png|css|dart|json))
   static_files: \1
   upload: (.*\.(html|js|png|css|dart|json))
   secure: always
 
 - url: /css/fonts/fontawesome-webfont.woff
   static_files: fontawesome-webfont.woff
   upload: fontawesome-webfont.woff
   secure: always
 
 libraries:
 - name: webapp2
   version: "2.5.2"