It's part of CSS Cascading and Inheritance Level 3: http://www.w3.org/TR/css-cascade-3/#inherit-initial See also https://developer.mozilla.org/en-US/docs/Web/CSS/unset Chrome and Firefox already support it, and it's "In Development" for Microsoft Edge. Testcase: http://jsfiddle.net/cvrebert/1w6bhom0/ Testcase's HTML: <div>A</div> <div>B</div> <div>C</div> Testcase's CSS: div { display: unset;/* in this case, same as inline */ }
<rdar://problem/22491420>
Created attachment 263197 [details] Patch
Attachment 263197 [details] did not pass style-queue: ERROR: Source/WebCore/css/CSSValue.h:49: enum members should use InterCaps with an initial capital letter. [readability/enum_casing] [4] ERROR: Source/WebCore/css/CSSValue.h:50: enum members should use InterCaps with an initial capital letter. [readability/enum_casing] [4] Total errors found: 2 in 23 files If any of these errors are false positives, please file a bug against check-webkit-style.
Comment on attachment 263197 [details] Patch View in context: https://bugs.webkit.org/attachment.cgi?id=263197&action=review > Source/WebCore/css/CSSParser.cpp:1951 > - > + Oopsy. > Source/WebCore/css/CSSUnsetValue.cpp:17 > + * Copyright (C) 2015 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. > + * > + * This library is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > + * Library General Public License for more details. > + * > + * You should have received a copy of the GNU Library General Public License > + * along with this library; see the file COPYING.LIB. If not, write to > + * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, > + * Boston, MA 02110-1301, USA. I thought we used this one for new files: * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. Or maybe it doesn't matter.
Fixed in r191151.
http://trac.webkit.org/changeset/191151