getTransformToElement: Include nested SVG's x/y attributes?

Dear list,

we are currently discussing coordinate systems of getTransformToElement and
co. since Firefox implements them in a different way as the other browsers
do.

The basic question is, in this example,

  <svg id="root">
    <svg id="inner" x="1" y="0"><rect id="r" x="1" y="0"/></svg>
  </svg>

what is the user coordinate system on the current element supposed to
be? Should inner.getTransformToElement(root) return an identity
matrix, because there is no 'transform' attribute on "inner", or
should it return a translation matrix by (1,0) because, according to
section 7.9, "inner"s user coordinate system has its origin there? Or,
again (0,0) because the new user coordinate system only affects the
children of  "inner" like "r"?


The full thread on Mozilla's bug tracker, including some demos, is here:
https://bugzilla.mozilla.org/show_bug.cgi?id=1064151

Greetings,
Simon