message: Fix conjugation
diff: @@ -104,5 +104,5 @@ Raven expects the browser to provide `window.JSON` and
  `standards mode
  <http://msdn.microsoft.com/en-us/library/cc288325(VS.85).aspx>`_. You can
  also use `json2.js <https://github.com/douglascrockford/JSON-js>`_ to
  -provide the JSON implementation in browsers/modes which doesn't support
  -native JSON
  +provide the JSON implementation in browsers/modes which don't support
  +native JSON.
  