box-shadow/text-shadow is ignored

[MurakamiShinyu]

box-shadow and text-shadow are in the supported features as "Support depends on browser capabilities", however it seems ignored.

Test
http://vivliostyle.github.io/vivliostyle.js/viewer/vivliostyle-viewer.html#x=https://rawgit.com/zopyx/css-paged-media-tutorial/master/lesson-box-styling/index.html

[kwkbtr]

It seems that we need to fix the parser for validators (defined in validation.txt).
Specifically, this line should be fixed, for values for shadows are comma-separated lists, not space-separated lists.