SVGDefinitionElement implementing SVGTests

When I converted SVG 2 to use Web IDL and reorganised the interfaces a 
bit, I introduced SVGDefinitionElement as a super-interface for elements 
like <mask>, <clipPath>, <linearGradient>, <filter>, <marker>, etc.  I 
have this too:

   SVGDefinitionElement implements SVGTests;

This is probably wrong, as we state in the section on the conditional 
processing attributes that they have no effect on <mask>, <clipPath> and 
<pattern>, although we don't mention the other kinds of definition element.

<marker> is a bit different since we have the new child <marker> element 
feature, where it makes more sense to allow these attributes:

   <path d="...">
     <marker position="50%" systemLanguage="..."> ... </marker>
   </path>

So I would suggest removing the "implements" statement above and 
replacing it with:

   SVGMarkerElement implements SVGTests;

Any disagreement?