Generates csv output for the runs

csv.js

let changesets = [
];
let url = "http://graphs.mozilla.org/api/test/runs/revisions?" + changesets.map(function(cset) {
  return "revision=" + cset;
}).join("&");
let req = new XMLHttpRequest();
req.open("GET", url, false);
req.send(null);
let result = JSON.parse(req.responseText).revisions;
let winxp = [];
let win7 = [];
changesets.forEach(function(cset) {
  let data = result[cset]["tp4"].test_runs;
  if (data["WINNT 5.1"]) {
    let tot = 0;
    data["WINNT 5.1"].forEach(function(run) { tot += run[3]; });
    winxp.push(Math.round(tot / data["WINNT 5.1"].length));
  }
  else {
    winxp.push(undefined);
  }
  if (data["WINNT 6.1"]) {
    let tot = 0;
    data["WINNT 6.1"].forEach(function(run) tot += run[3]);
    win7.push(Math.round(tot / data["WINNT 6.1"].length));
  }
  else {
    win7.push(undefined);
  }
});
let str = [];
for (let i = 0; i < changesets.length; i++) {
  str.push([changesets[i], winxp[i], win7[i]].join(", "));
}
str.join("\n");