'd' presentation attribute: use path() function

This brings the spec, the web platform tests and the only
shipping implementation (Chrome) into consistency:

  none | path(<string>)

closes #320

master/paths.html

@@ -237,7 +237,7 @@ <h3 id="TheDProperty">Specifying path data: the <span class='property'>'d'</span
   </tr>
   <tr>
     <th>Value:</th>
-    <td>none | <a>&lt;string&gt;</a></td>
+    <td>none | path(<a>&lt;string&gt;</a>)</td>
   </tr>
   <tr>
     <th>Initial:</th>
@@ -303,6 +303,10 @@ <h3 id="TheDProperty">Specifying path data: the <span class='property'>'d'</span
   <a href="https://w3c.github.io/web-animations/#discrete-animation-type-section">discrete</a>
   animation type.
 </p>
+<p>
+  Lowercase commands (with relative coordinates) are converted to equivalent uppercase commands
+  (with absolute coordinates) before determining if the path data strings have the same structure.
+</p>
 <p>
   If the list of path data commands have the same structure, then each
   parameter to each path data command must be
@@ -313,16 +317,9 @@ <h3 id="TheDProperty">Specifying path data: the <span class='property'>'d'</span
   to be a value of one/true.
 </p>
 
-<p class="annotation">
-  Resolved that "d will become a presentation attribute (no name
-  change) with path data string as value" at
-  <a href="https://www.w3.org/2016/04/21-svg-minutes.html">London
-  Editor's Meeting</a>.
-</p>
-
 </div>
 
-<p>The following sections list the commands that canbe used
+<p>The following sections list the commands that can be used
 in path data strings.  Those that
 draw straight line segments include the <a href="paths.html#PathDataLinetoCommands">lineto commands</a>
 (<strong>L</strong>, <strong>l</strong>,

master/propidx.html

@@ -137,6 +137,16 @@ <h1>Property Index</h1>
           <td><a href="https://www.w3.org/TR/2008/REC-CSS2-20080411/media.html#visual-media-group">visual</a>, <a href="https://www.w3.org/TR/2008/REC-CSS2-20080411/media.html#interactive-media-group">          interactive</a></td>
           <td>yes</td>
         </tr>
+        <tr>
+          <th><a>'d'</a></th>
+          <td>none | path(<a>&lt;string&gt;</a>)</td>
+          <td>none</td>
+          <td><a>'path'</a> elements</td>
+          <td>no</td>
+          <td>N/A</td>
+          <td><a href="https://www.w3.org/TR/2008/REC-CSS2-20080411/media.html#visual-media-group">visual</a></td>
+          <td>yes</td>
+        </tr>
         <tr>
           <th><a>'direction'</a></th>
           <td>ltr | rtl </td>