SVG renders children="[Object object]" into DOM

[zpao]

See http://jsfiddle.net/e91q5089/ for a basic example.

I'm assuming there's some step in the new SVG code that we just need to remove the children key if we consume it as a React prop.

[zpao]

Going to leave this open to ensure we block even though @gaearon wrote fix before I finished submitting (do you ever sleep Dan!?)

[gaearon]

I sleep incrementally.
FWIW the fix is in #6164.