mozilla/servo — pull request #1631 by recrack (2014-02-06 07:27:16+00:00)
Title: Impl background image property and and others.

for #777 #800

- support(http://www.w3.org/TR/CSS21/colors.html#background)
- background: url(foo.png)
- background: url(data:image/png;base64...)
- background-image: url(foo.png)
- background-image: url(data:image/png;base64...)

- not support(http://www.w3.org/TR/css3-background/)