Content Scope Runner

An extension of the Content Script Injection technique, this snippet automatically runs the entire user script in the content scope.

if(typeof __PAGE_SCOPE_RUN__ == 'undefined') {
   (function page_scope_runner() {
      var script = document.createElement('script');
      script.setAttribute("type", "application/javascript");
      script.textContent = "(function() { var __PAGE_SCOPE_RUN__ = 'yes'; (" + page_scope_runner.caller.toString() + ")(); })();";
      document.documentElement.appendChild(script);
      document.documentElement.removeChild(script);
   })();
   return;
}

As soon as execution reaches this code, the entire script will be injected into the page and re-run. Thus you need not worry about any of the security restrictions from XPCNativeWrappers in the Greasemonkey sandbox. You also will, of course, not have access to any of the APIs.

Explanation

The code block first checks to see if it is being run inside the page by looking for a marker it knows about. If the marker is not present, the block creates and injects a script element that starts by setting the aforementioned marker variable and finishes by executing the text of the userscript. Finally, the block calls `return`, ending execution.