Remove unnecessary error flash classes

static/utilities.less

@@ -64,13 +64,3 @@ div > .inline-block-tight:last-child {
     margin-left: 0;
   }
 }
-
-.error {
-  -webkit-animation: flash-error 0.3s ease-in;
-}
-
-@-webkit-keyframes flash-error {
-  0% { background: @background-color-error; }
-
-  100% { background: auto; }
-}