ISSUE-2287 (empty_clippath): Consider clarifying empty clipPath behaviour [SVG Full 1.1]

ISSUE-2287 (empty_clippath): Consider clarifying empty clipPath behaviour [SVG Full 1.1]

http://www.w3.org/Graphics/SVG/WG/track/issues/2287

Raised by: Erik Dahlström
On product: SVG Full 1.1

We might want to consider clarifying the behaviour for how empty clipPaths affect what they're applied on. And also how display and visibility affect children of <clipPath> when generating the clippath.

Some cases to consider (all tested by [1]):
a) <clipPath> with no children
b) <clipPath> with children that have display="none"
c) <clipPath> with children that have visibility="hidden"
d) does clip-path="url(#brokenlink)" mean everything is clipped, or nothing is clipped?

Testresults for [1] in order a,b,c,d:
Safari 4:    x, y*, x, y
Opera 10:    x, x,  x, y
Firefox 3.5: x, x,  x, x
Batik 1.7:   y, y,  y, f

x) clips all
y) clips nothing
f) error dialog
*) visibilty=hidden children contribute to clippath

[1] http://dev.w3.org/SVG/profiles/1.1F2/ua-tests/clippath-empty.svg