[cssom] Use more specific return type for ownerNode and make it nullable.

Author: Simon Pieters

cssom/Overview.html

@@ -18,7 +18,7 @@ <h1 id="cssom">CSS Object Model (CSSOM)</h1>
 
    <!-- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
 
-   <h2 class="no-num no-toc" id="w3c-doctype">Editor's Draft 8 May 2013</h2>
+   <h2 class="no-num no-toc" id="w3c-doctype">Editor's Draft 9 May 2013</h2>
 
    <dl>
 
@@ -83,7 +83,7 @@ <h2 class="no-num no-toc" id="sotd">Status of this Document</h2>
   can be found in the
   <a href="http://www.w3.org/TR/">W3C technical reports index at http://www.w3.org/TR/.</a></em>
 
-  <p class="dontpublish">This is the 8 May 2013 Editor's Draft of CSSOM. Please send comments to
+  <p class="dontpublish">This is the 9 May 2013 Editor's Draft of CSSOM. Please send comments to
   <a href="mailto:www-style@w3.org?subject=%5Bcssom%5D%20">www-style@w3.org</a>
   (<a href="http://lists.w3.org/Archives/Public/www-style/">archived</a>)
   with <samp>[cssom]</samp> at the start of the subject line.
@@ -914,7 +914,7 @@ <h4 id="the-stylesheet-interface"><span class="secno">6.1.1 </span>The <code><a
 <pre class="idl"><span class="idlInterface" id="widl-def-StyleSheet">interface <a class="idlInterfaceID" href="#widl-CSSImportRule-styleSheet">StyleSheet</a> {
 <span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>DOMString</a></span> <span class="idlAttrName"><a href="#widl-StyleSheet-type">type</a></span>;</span>
 <span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>DOMString</a>?</span> <span class="idlAttrName"><a href="#widl-StyleSheet-href">href</a></span>;</span>
-<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>Node</a></span> <span class="idlAttrName"><a href="#widl-StyleSheet-ownerNode">ownerNode</a></span>;</span>
+<span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>union</a>?</span> <span class="idlAttrName"><a href="#widl-StyleSheet-ownerNode">ownerNode</a></span>;</span>
 <span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>StyleSheet</a>?</span> <span class="idlAttrName"><a href="#widl-StyleSheet-parentStyleSheet">parentStyleSheet</a></span>;</span>
 <span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>DOMString</a>?</span> <span class="idlAttrName"><a href="#widl-StyleSheet-title">title</a></span>;</span>
 <span class="idlAttribute">    readonly attribute <span class="idlAttrType"><a>MediaList</a></span> <span class="idlAttrName"><a href="#widl-StyleSheet-media">media</a></span>;</span>
@@ -930,9 +930,9 @@ <h4 id="the-stylesheet-interface"><span class="secno">6.1.1 </span>The <code><a
 <dd>
 <p>The <code><a href="#widl-CSSImportRule-href">href</a></code> attribute must return the <a href="#style-sheet-location">style sheet location</a> or <code>null</code> if none.</p>    <p class="issue">What should the default value be if not known or specified upon creation? an empty string or <code>null</code>?</dd>
 <dt class="attribute" id="widl-StyleSheet-ownerNode">
-<dfn id="widl-StyleSheet-ownerNode"><code>ownerNode</code></dfn> of type <span class="idlAttrType"><a>Node</a></span>, readonly</dt>
+<dfn id="widl-StyleSheet-ownerNode"><code>ownerNode</code></dfn> of type <span class="idlAttrType"><a>union</a>?</span>, readonly</dt>
 <dd>
-<p>The <code><a href="#widl-StyleSheet-ownerNode">ownerNode</a></code> attribute must return the <a href="#style-sheet-owner-node">style sheet owner node</a>.</p>    <p class="issue">Should <code><a href="#widl-StyleSheet-ownerNode">ownerNode</a></code> be nullable?</dd>
+<p>The <code><a href="#widl-StyleSheet-ownerNode">ownerNode</a></code> attribute must return the <a href="#style-sheet-owner-node">style sheet owner node</a> or <code>null</code> if there is none.</p>    <p class="issue">The return type in the IDL is supposed to be <code>(Element or ProcessingInstruction)?</code>.</dd>
 <dt class="attribute" id="widl-StyleSheet-parentStyleSheet">
 <dfn id="widl-StyleSheet-parentStyleSheet"><code>parentStyleSheet</code></dfn> of type <span class="idlAttrType"><a>StyleSheet</a>?</span>, readonly</dt>
 <dd>

cssom/idl/StyleSheet.idl

@@ -21,10 +21,10 @@ interface StyleSheet {
   readonly attribute DOMString? href;
 
   [Documentation=
-   "<p>The {@name} {@type} must return the <span>style sheet owner node</span>.</p>\
-    <p class='issue'>Should {@name} be nullable?</p>"
+   "<p>The {@name} {@type} must return the <span>style sheet owner node</span> or <code>null</code> if there is none.</p>\
+    <p class=issue>The return type in the IDL is supposed to be <code>(Element or ProcessingInstruction)?</code>.</p>"
   ]
-  readonly attribute Node ownerNode;
+  readonly attribute (Element or ProcessingInstruction)? ownerNode;
 
   [Documentation=
    "<p>The {@name} {@type} must return the <span>style sheet parent</span> or <code>null</code> if there is none.</p>"