message: Docs: mention webworker support, clarify old browser support
diff: @@ -99,10 +99,14 @@ To use Raven with ES2015 (ES6) imports:
  Requirements
  ~~~~~~~~~~~~
  -Raven expects the browser to provide `window.JSON` and
  -`window.JSON.stringify`. In Internet Explorer 8+ these are available in
  -`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 don't support
  -native JSON.
  +Raven supports IE8+ and all other modern browsers, and works in Web Workers.
  +
  +Raven requires the browser JavaScript environment to provide:
  +- Either `XHR Level 2 <http://caniuse.com/#feat=xhr2>`_ (IE10+, all other modern browsers)
  + or `XDomainRequest <https://developer.mozilla.org/en-US/docs/Web/API/XDomainRequest>`_ (IE8, IE9)
  +- A global ``JSON`` object with ``JSON.stringify`` (IE8+ `standards mode
  +<http://msdn.microsoft.com/en-us/library/cc288325(VS.85).aspx>`_, all other modern browsers)
  +
  +Raven does not support IE 7 or other older browsers which do not provide the required features listed above.
  +On those older browsers, Raven.js is designed to fail gracefully; including it on your page
  +will have no effect, but it won't collect and report uncaught exceptions.
  \ No newline at end of file
  