Styling option should not override option:checked UA style

Source/core/css/html.css

 /*
  * The default style sheet used to render HTML.
  *
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 739 matching lines @@
     box-sizing: border-box;
     align-items: center;
     border: 1px solid;
     white-space: pre;
     -webkit-rtl-ordering: logical;
     color: black;
     background-color: white;
     cursor: default;
 }
 
-select[size],
-select[multiple],
-select[size][multiple] {
+select:-internal-list-box {
     -webkit-appearance: listbox;
     align-items: flex-start;
     border: 1px inset gray;
     border-radius: initial;
     overflow-x: hidden;
     overflow-y: scroll;
     vertical-align: text-bottom;
     -webkit-user-select: none;
     white-space: nowrap;
 }
 
-select[size="0"],
-select[size="1"] {
-    -webkit-appearance: menulist;
-    align-items: center;
-    border-width: 1px;
-    border-style: solid;
-    border-color: initial;
-    border-radius: 5px;
-    overflow-x: initial;
-    overflow-y: initial;
-    vertical-align: initial;
-    -webkit-user-select: initial;
-    white-space: pre;
-}
-
 optgroup {
     font-weight: bolder;
     display: block;
 }
 
 option {
     font-weight: normal;
     display: block;
     padding: 0 2px 1px 2px;
     white-space: pre;
     min-height: 1.2em;
 }
 
-select:focus[size] option:checked,
-select:focus[multiple] option:checked,
-select:focus[size][multiple] option:checked {
-    background-color: -internal-active-list-box-selection;
-    color: -internal-active-list-box-selection-text;
+select:-internal-list-box:focus option:checked {
+    background-color: -internal-active-list-box-selection !important;
+    color: -internal-active-list-box-selection-text !important;
 }
 
-select[size] option:checked,
-select[multiple] option:checked,
-select[size][multiple] option:checked {
-    background-color: -internal-inactive-list-box-selection;
-    color: -internal-inactive-list-box-selection-text;
+select:-internal-list-box option:checked {
+    background-color: -internal-inactive-list-box-selection !important;
+    color: -internal-inactive-list-box-selection-text !important;
 }
 
-select[size="0"] option:checked,
-select[size="1"] option:checked,
-select:focus[size="0"] option:checked,
-select:focus[size="1"] option:checked {
-    background-color: initial;
-    color: initial;
+select:-internal-list-box:disabled option:checked,
+select:-internal-list-box option:checked:disabled {
+    color: gray !important;
 }
 
-select:disabled option:checked,
-select:disabled[size] option:checked,
-select:disabled[multiple] option:checked,
-select:disabled[size][multiple] option:checked,
-option:checked:disabled,
-select[size] option:checked:disabled,
-select[multiple] option:checked:disabled,
-select[size][multiple] option:checked:disabled {
-    color: gray;
-}
 
 output {
     display: inline;
 }
 
 /* meter */
 
 meter {
     -webkit-appearance: meter;
     box-sizing: border-box;
@@ skipping 248 matching lines @@
 @page {
     /* FIXME: Define the right default values for page properties. */
     size: auto;
     margin: auto;
     padding: 0px;
     border-width: 0px;
 }
 
 /* noscript is handled internally, as it depends on settings. */