Added preventDefault (#3137)

webapp/components/create_comment.jsx

@@ -225,6 +225,7 @@ class CreateComment extends React.Component {
         }
 
         if ((e.ctrlKey || e.metaKey) && !e.altKey && !e.shiftKey && e.keyCode === KeyCodes.UP) {
+            e.preventDefault();
             const lastPost = PostStore.getCurrentUsersLatestPost(this.props.channelId, this.props.rootId);
             if (!lastPost) {
                 return;

webapp/components/create_post.jsx

@@ -374,6 +374,7 @@ class CreatePost extends React.Component {
         }
 
         if ((e.ctrlKey || e.metaKey) && !e.altKey && !e.shiftKey && e.keyCode === KeyCodes.UP) {
+            e.preventDefault();
             const channelId = ChannelStore.getCurrentId();
             const lastPost = PostStore.getCurrentUsersLatestPost(channelId);
             if (!lastPost) {