Reverted New Messages indicator in center channel (#2853)

webapp/sass/layout/_post.scss

@@ -170,33 +170,6 @@ body.ios {
     }
 }
 
-.post-list__new-messages-below {
-    @include single-transition(bottom .5s cubic-bezier(86, 0, 07, 1));
-    @include opacity(.9);
-    background-color: $black;
-    border-radius: 1em;
-    bottom: 10px;
-    color: $white;
-    cursor: pointer;
-    display: inline-block;
-    left: 50%;
-    padding: .3em .75em;
-    position: absolute;
-    transform: translateX(-50%);
-
-    &[hidden] {
-        bottom: -30px;
-    }
-
-    .fa {
-        font-size: 17px;
-        font-weight: bold;
-        margin-right: 1px;
-        position: relative;
-        top: 1px;
-    }
-}
-
 .file-overlay {
     color: $white;
     font-size: em(20px);