[cssom-view] img.x/y return 0 if it's not rendered.

Author: Simon Pieters

cssom-view/Overview.html

@@ -1487,11 +1487,11 @@ <h2 id="excensions-to-the-htmlimageelement-interface"><span class="secno">9 </sp
 
 <p>The <dfn id="dom-htmlimageelement-x" title="dom-HTMLImageElement-x"><code>x</code></dfn> attribute, on getting, must return the x-coordinate of the left <a href="#border-edge">border edge</a> of the
 first <a href="#css-layout-box">CSS layout box</a> associated with the element, relative to the <a href="#initial-containing-block">initial containing block</a> origin, ignoring any
-<a href="#transforms">transforms</a> that apply to the element and its ancestors.
+<a href="#transforms">transforms</a> that apply to the element and its ancestors, or zero if there is no <a href="#css-layout-box">CSS layout box</a>.
 
 <p>The <dfn id="dom-htmlimageelement-y" title="dom-HTMLImageElement-y"><code>y</code></dfn> attribute, on getting, must return the y-coordinate of the top <a href="#border-edge">border edge</a> of the
 first <a href="#css-layout-box">CSS layout box</a> associated with the element, relative to the <a href="#initial-containing-block">initial containing block</a> origin, ignoring any
-<a href="#transforms">transforms</a> that apply to the element and its ancestors.
+<a href="#transforms">transforms</a> that apply to the element and its ancestors, or zero if there is no <a href="#css-layout-box">CSS layout box</a>.
 
 
 <h2 id="extensions-to-the-range-interface"><span class="secno">10 </span>Extensions to the <code title="">Range</code> Interface</h2>

cssom-view/Overview.src.html

@@ -1443,11 +1443,11 @@ <h2>Excensions to the <code title>HTMLImageElement</code> Interface</h2>
 
 <p>The <dfn title=dom-HTMLImageElement-x><code>x</code></dfn> attribute, on getting, must return the x-coordinate of the left <span>border edge</span> of the
 first <span>CSS layout box</span> associated with the element, relative to the <span>initial containing block</span> origin, ignoring any
-<span>transforms</span> that apply to the element and its ancestors.
+<span>transforms</span> that apply to the element and its ancestors, or zero if there is no <span>CSS layout box</span>.
 
 <p>The <dfn title=dom-HTMLImageElement-y><code>y</code></dfn> attribute, on getting, must return the y-coordinate of the top <span>border edge</span> of the
 first <span>CSS layout box</span> associated with the element, relative to the <span>initial containing block</span> origin, ignoring any
-<span>transforms</span> that apply to the element and its ancestors.
+<span>transforms</span> that apply to the element and its ancestors, or zero if there is no <span>CSS layout box</span>.
 
 
 <h2>Extensions to the <code title>Range</code> Interface</h2>