code: function preloadFontFace(data, onload, onerror) {
              var font = new FontFace(data.name, data.src);
              // loading promise
              font.load().then(function() {
                  // apply the font after the font has finished downloading
                  document.fonts.add(font);
                  document.body.style.fontFamily = data.name;
                  // onloaded callback
                  onload();
              }, function (e) {
                  // rejected
                  onerror(data.name);
              });
          }
docs: load a font face
  @example
  preloadFontFace(
  name: "'kenpixel'", type: "fontface",  src: "url('data/font/kenvector_future.woff2')"
  ]);
  @ignore