Proper handling of SVG and rgba()

I was looking at Webkit, specifiaclly bug 16183 (
https://bugs.webkit.org/show_bug.cgi?id=16183) - SVG doesn't support rgba()
colors.  I was planning on fixing this but after reading the SVG spec at
http://www.w3.org/TR/SVG11/ which states that SVG supports CSS2 color
specifications I'm unsure if this should be fixed or not. rgba() was
introduced with CSS3 so is technically not supported by SVG.

Looking at other implementations Chrome and webkit-head both render a rgba()
color as pure black.  Safari 4.0.5 I've seen render it as either black or
missing.  Firefox does render it properly.  Batiq fails to render and gives
an error: "The attribute "stroke" represents an invalid CSS value ("rgba(0,
255, 0, 0.5)")."

Looking at this bug from an end user perspective it would be good to add
this feature in as its likely that people will build sites that aren't
strictly compliant and would want things to just work.  However I'm always
wary of making changes that go against a published standard as that path can
lead to ugliness, divergent standards and future headaches.

What I'm looking for from the community is feedback on what the right thing
to do here with respect to webkit is.  Is it worth the convenience to the
user to add support for rgba() to the SVG code?

-Jon