Fix lodaing missing messages after search bug (#5080)

webapp/actions/global_actions.jsx

@@ -256,7 +256,7 @@ export function emitLoadMorePostsFocusedTopEvent() {
 }
 
 export function loadMorePostsTop(id, isFocusPost) {
-    const earliestPostId = PostStore.getEarliestPost(id).id;
+    const earliestPostId = PostStore.getEarliestPostFromPage(id).id;
     if (PostStore.requestVisibilityIncrease(id, Constants.POST_CHUNK_SIZE)) {
         loadPostsBefore(earliestPostId, 0, Constants.POST_CHUNK_SIZE, isFocusPost);
     }

webapp/actions/post_actions.jsx

@@ -167,6 +167,7 @@ export function loadPostsPage(channelId = ChannelStore.getCurrentId(), max = Con
                 before: true,
                 numRequested: numPosts,
                 checkLatest: true,
+                checkEarliest: true,
                 post_list: data
             });
 
@@ -195,6 +196,7 @@ export function loadPostsBefore(postId, offset, numPost, isPost) {
                 type: ActionTypes.RECEIVED_POSTS,
                 id: channelId,
                 before: true,
+                checkEarliest: true,
                 numRequested: numPost,
                 post_list: data,
                 isPost