Make line height calculation quirk aware of writing modes

This appears to match WebKit and Chromium.

Part of #5.

Overview.bs

@@ -311,8 +311,10 @@ box had a 'line-height' of zero.
 
 <ul>
 
- <li><p>The 'border-right-width', 'border-left-width', 'padding-right' and 'padding-left' properties
- have a <a>used value</a> of zero.
+ <li><p>The 'border-top-width', 'border-bottom-width', 'padding-top' and 'padding-bottom' properties
+ have a <a>used value</a> of zero and the box has a <a>vertical writing mode</a>, or the
+ 'border-right-width', 'border-left-width', 'padding-right' and 'padding-left' properties have a
+ <a>used value</a> of zero and the box has a <a>horizontal writing mode</a>.
 
  <!-- This matches WebKit. Presto and IE9 don't have this [Presto has now implemented this
 (CORE-19183)]. Gecko has this rule for all margins, paddings and borders. -->

Overview.html

@@ -20,7 +20,7 @@
    <p data-fill-with="logo"><a class="logo" href="https://whatwg.org/"> <img alt="WHATWG" height="100" src="https://resources.whatwg.org/logo.svg"> </a> </p>
    <hgroup>
     <h1 class="p-name no-ref" id="title">Quirks Mode</h1>
-    <h2 class="no-num no-toc no-ref heading settled" id="subtitle"><span class="content">Living Standard — Last Updated <time class="dt-updated" datetime="2016-06-30">30 June 2016</time></span></h2>
+    <h2 class="no-num no-toc no-ref heading settled" id="subtitle"><span class="content">Living Standard — Last Updated <time class="dt-updated" datetime="2016-07-06">6 July 2016</time></span></h2>
    </hgroup>
    <div data-fill-with="spec-metadata">
     <dl>
@@ -267,8 +267,8 @@ <h3 class="heading settled" data-algorithm="The line height calculation quirk" d
 box had a <a class="property" data-link-type="propdesc" href="https://drafts.csswg.org/css2/visudet.html#propdef-line-height">line-height</a> of zero. </p>
    <ul>
     <li>
-     <p>The <a class="property" data-link-type="propdesc" href="https://drafts.csswg.org/css-backgrounds-3/#border-right-width">border-right-width</a>, <a class="property" data-link-type="propdesc" href="https://drafts.csswg.org/css-backgrounds-3/#border-left-width">border-left-width</a>, <a class="property" data-link-type="propdesc" href="https://drafts.csswg.org/css2/box.html#propdef-padding-right">padding-right</a> and <a class="property" data-link-type="propdesc" href="https://drafts.csswg.org/css2/box.html#propdef-padding-left">padding-left</a> properties
- have a <a data-link-type="dfn" href="https://drafts.csswg.org/css-cascade-4/#used-value">used value</a> of zero. </p>
+     <p>The <a class="property" data-link-type="propdesc" href="https://drafts.csswg.org/css-backgrounds-3/#border-top-width">border-top-width</a>, <a class="property" data-link-type="propdesc" href="https://drafts.csswg.org/css-backgrounds-3/#border-bottom-width">border-bottom-width</a>, <a class="property" data-link-type="propdesc" href="https://drafts.csswg.org/css2/box.html#propdef-padding-top">padding-top</a> and <a class="property" data-link-type="propdesc" href="https://drafts.csswg.org/css2/box.html#propdef-padding-bottom">padding-bottom</a> properties
+ have a <a data-link-type="dfn" href="https://drafts.csswg.org/css-cascade-4/#used-value">used value</a> of zero and the box has a <a data-link-type="dfn" href="https://drafts.csswg.org/css-writing-modes-3/#vertical-writing-mode">vertical writing mode</a>, or the <a class="property" data-link-type="propdesc" href="https://drafts.csswg.org/css-backgrounds-3/#border-right-width">border-right-width</a>, <a class="property" data-link-type="propdesc" href="https://drafts.csswg.org/css-backgrounds-3/#border-left-width">border-left-width</a>, <a class="property" data-link-type="propdesc" href="https://drafts.csswg.org/css2/box.html#propdef-padding-right">padding-right</a> and <a class="property" data-link-type="propdesc" href="https://drafts.csswg.org/css2/box.html#propdef-padding-left">padding-left</a> properties have a <a data-link-type="dfn" href="https://drafts.csswg.org/css-cascade-4/#used-value">used value</a> of zero and the box has a <a data-link-type="dfn" href="https://drafts.csswg.org/css-writing-modes-3/#horizontal-writing-mode">horizontal writing mode</a>. </p>
     <li>
      <p>It either contains no text or it contains only collapsed whitespace. </p>
    </ul>