fix: Fix fullscreen functionality in mobile.html

docs/uncompiled/artplayer/index.js

@@ -1884,10 +1884,10 @@ function fullscreenMix(art) {
             set (value) {
                 if (value) {
                     art.state = "fullscreen";
-                    requestFullscreen();
+                    requestFullscreen.call($video);
                     art.emit("fullscreen", true);
                 } else {
-                    exitFullscreen();
+                    exitFullscreen.call(document);
                     art.emit("fullscreen", false);
                 }
                 art.emit("resize");