title: Global Variable in safari extension
body: <p>How can i have a global variable in <strong>safari extension</strong> that can be acceded from injected script, 
  and can be saved for the next launch after safari is closed.
  <br/><br/>and by global i mean static.
  <br/>so that all injected script access the same version of that variable not every injected script has it's own.
  <br/>and not like <strong>localStorage</strong> that is per domain.</p>