Bug 1959298 - use search params in about:memory, r=mccr8

  appendElementWithText(gFooter, "div", "legend", legendText1);

  appendElementWithText(gFooter, "div", "legend hiddenOnMobile", legendText2);

  // See if we're loading from a file.  (Because about:memory is a non-standard

  // URL, location.search is undefined, so we have to use location.href

  // instead.)

  let search = location.href.split("?")[1];

  if (search) {

    let searchSplit = search.split("&");

    for (let s of searchSplit) {

      if (s.toLowerCase().startsWith("file=")) {

        let filename = s.substring("file=".length);

        updateAboutMemoryFromFile(decodeURIComponent(filename));

        return;

      }

    }

  // See if we're loading from a file.

  let { searchParams } = URL.fromURI(document.documentURIObject);

  let fileParam = searchParams.get("file");

  if (fileParam) {

    updateAboutMemoryFromFile(fileParam);

  }

};