[css-ruby] Change ruby pairing rules to only operate on anonymous annotations (i.e. content directly contained by an <rtc>) per Xidorn's implementation feedback. <http://www.w3.org/mid/54667A6B.6060805@inkedblade.net> Might need to coordinate with HTML spec on this point, though.

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extra : rebase_source : 2ec35186f0b1e56fa2f5c2d715d014ef147f06ed

Author: fantasai