Just this morning I setup a greasemonkey script to rewrite those URLs to a local webserver (things like ajax.googleapis.com serving things like jquery). Pages load faster now too. Very limited, but works in many cases:

  // ==UserScript==
  // @name     localize ajax googleapis
  // @version  1
  // @grant    none
  // @run-at  document-start
  var scripts = document.getElementsByTagName("script");
  for (i=0; i<scripts.length; i++) {
    var parent = scripts[i].parentElement;
    var url = new URL(scripts[i].src);
    if (url.host === "ajax.googleapis.com") {
      url.host = "ajax.googleapis.com.local";
      var newscript = document.createElement("script");
      newscript.type="text/javascript";
      newscript.src = url;
      parent.insertBefore(newscript, scripts[i]);    
      parent.removeChild(scripts[i]);
      console.log("Rewrote url as " + url); 
    }
  }
  // ==/UserScript==

EDIT: I just read the other comments and installed decentraleyes. I'm sure it's way better than this grease I just posted.