Do not send push notifications for channels being actively viewed (#3931)

webapp/actions/post_actions.jsx

@@ -19,7 +19,7 @@ const Preferences = Constants.Preferences;
 export function handleNewPost(post, msg) {
     if (ChannelStore.getCurrentId() === post.channel_id) {
         if (window.isActive) {
-            AsyncClient.updateLastViewedAt();
+            AsyncClient.updateLastViewedAt(null, false);
         } else {
             AsyncClient.getChannel(post.channel_id);
         }

webapp/actions/websocket_actions.jsx

@@ -174,7 +174,7 @@ function handlePostEditEvent(msg) {
     // Update channel state
     if (ChannelStore.getCurrentId() === msg.channel_id) {
         if (window.isActive) {
-            AsyncClient.updateLastViewedAt();
+            AsyncClient.updateLastViewedAt(null, false);
         }
     }
 }