Spin button in input[type=number] should not ignore paddings.

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 555 matching lines @@
     display: inline;
     font: inherit !important;
 }
 
 input[type="date"]::-webkit-inner-spin-button,
 input[type="datetime"]::-webkit-inner-spin-button,
 input[type="datetime-local"]::-webkit-inner-spin-button,
 input[type="month"]::-webkit-inner-spin-button,
 input[type="time"]::-webkit-inner-spin-button,
 input[type="week"]::-webkit-inner-spin-button {
-    display: inline-block;
-    position: static;
+    /* FIXME: Remove height. */
+    height: 1.5em;
     -webkit-margin-start: 2px;
 }
 
 #else
 input[type="date"],
 input[type="datetime-local"],
 input[type="month"],
 input[type="time"],
 input[type="week"] {
     align-items: center;
     -webkit-appearance: menulist;
     background-color: ButtonFace;
     border: 1px solid #a9a9a9;
     display: -webkit-inline-flex;
     overflow: hidden;
     width: 10em;
 }
 
 input::-webkit-date-and-time-value {
     margin: 1px 24px 1px 4px;
     white-space: pre;
 }
 #endif
 
 input::-webkit-inner-spin-button {
     -webkit-appearance: inner-spin-button;
-    display: block;
-    position: relative;
+    display: inline-block;
     cursor: default;
-    /* This height property is ignored for input type "number" and others which
-     * use RenderTextControlSingleLine as renderer which sets height of spin
-     * button in layout(). */
-    height: 1.5em;
-    vertical-align: top;
     flex: none;
+    align-self: stretch;
     -webkit-user-select: none;
     -webkit-user-modify: read-only !important;
     opacity: 0;
     pointer-events: none;
 }
 
 input:enabled:read-write:-webkit-any(:focus,:hover)::-webkit-inner-spin-button {
     opacity: 1;
     pointer-events: auto;
 }
@@ skipping 546 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. */