fix: Improve websocket reliability (#1470)

* check connection on page visibility change

* fix: SocketPresence account for socket changing

app/utils/pageVisibility.js

@@ -0,0 +1,25 @@
+// @flow
+let hidden = "hidden";
+let visibilityChange = "visibilitychange";
+
+if ("hidden" in document) {
+  hidden = "hidden";
+  visibilityChange = "visibilitychange";
+} else if ("mozHidden" in document) {
+  // Firefox up to v17
+  hidden = "mozHidden";
+  visibilityChange = "mozvisibilitychange";
+} else if ("webkitHidden" in document) {
+  // Chrome up to v32, Android up to v4.4, Blackberry up to v10
+  hidden = "webkitHidden";
+  visibilityChange = "webkitvisibilitychange";
+}
+
+export function getVisibilityListener(): string {
+  return visibilityChange;
+}
+
+export function getPageVisible(): boolean {
+  // $FlowFixMe
+  return !document[hidden];
+}