[cssom-view] Ignore transforms for MouseEvent#offsetX/Y. https://www.w3.org/Bugs/Public/show_bug.cgi?id=15430

Author: Simon Pieters

cssom-view/Overview.html

@@ -1571,15 +1571,17 @@ <h2 id="extensions-to-the-mouseevent-interface"><span class="secno">10 </span>Ex
 
 <ol>
  <li><p>If the event's <a class="external" data-anolis-spec="dom" href="http://dom.spec.whatwg.org/#dispatch-flag">dispatch flag</a> is set, return the x-coordinate of the position where the event occurred relative to the
- origin of the <a href="#padding-edge">padding edge</a> of the target node and terminate these steps.
+ origin of the <a href="#padding-edge">padding edge</a> of the target node, ignoring the <a href="#transforms">transforms</a> that apply to the element and its ancestors, and terminate
+ these steps.
  <li><p>Return the value of the event's <code title="dom-MouseEvent-pageX"><a href="#dom-mouseevent-pagex">pageX</a></code> attribute.
 </ol>
 
 <p>The <dfn id="dom-mouseevent-offsety" title="dom-MouseEvent-offsetY"><code>offsetY</code></dfn> attribute must follow these steps:
 
 <ol>
  <li><p>If the event's <a class="external" data-anolis-spec="dom" href="http://dom.spec.whatwg.org/#dispatch-flag">dispatch flag</a> is set, return the y-coordinate of the position where the event occurred relative to the
- origin of the <a href="#padding-edge">padding edge</a> of the target node and terminate these steps.
+ origin of the <a href="#padding-edge">padding edge</a> of the target node, ignoring the <a href="#transforms">transforms</a> that apply to the element and its ancestors, and terminate
+ these steps.
  <li><p>Return the value of the event's <code title="dom-MouseEvent-pageY"><a href="#dom-mouseevent-pagey">pageY</a></code> attribute.
 </ol>
 

cssom-view/Overview.src.html

@@ -1532,15 +1532,17 @@ <h2>Extensions to the <code title>MouseEvent</code> Interface</h2>
 
 <ol>
  <li><p>If the event's <span data-anolis-spec=dom>dispatch flag</span> is set, return the x-coordinate of the position where the event occurred relative to the
- origin of the <span>padding edge</span> of the target node and terminate these steps.
+ origin of the <span>padding edge</span> of the target node, ignoring the <span>transforms</span> that apply to the element and its ancestors, and terminate
+ these steps.
  <li><p>Return the value of the event's <code title=dom-MouseEvent-pageX>pageX</code> attribute.
 </ol>
 
 <p>The <dfn title=dom-MouseEvent-offsetY><code>offsetY</code></dfn> attribute must follow these steps:
 
 <ol>
  <li><p>If the event's <span data-anolis-spec=dom>dispatch flag</span> is set, return the y-coordinate of the position where the event occurred relative to the
- origin of the <span>padding edge</span> of the target node and terminate these steps.
+ origin of the <span>padding edge</span> of the target node, ignoring the <span>transforms</span> that apply to the element and its ancestors, and terminate
+ these steps.
  <li><p>Return the value of the event's <code title=dom-MouseEvent-pageY>pageY</code> attribute.
 </ol>