The motivation is that Chrome XBL stylesheets can be parsed under author
level, but we allow some event-state pseudo classes like
:-moz-handled-clicktoplay to be used.
Also synchronize the privilege of pseudo classes in
non_ts_pseudo_class_list.rs and nsCSSPseudoClassList.h (except :fullscreen).
MozReview-Commit-ID: 8fUjjC8hbQO
We parse when assigning using the namespaces of the stylesheet. It isn't
clear if the spec says to do that (Firefox doesn't support the setter at
all, Chrome does, Safari doesn't); the spec issue is here:
https://github.com/w3c/csswg-drafts/issues/1511
Also fix ToCss implementation of AttrSelectorOperator to not pad with
spaces, to conform with CSSOM. This means we have to update some unit
tests that expect operators with spaces around them in attribute
selectors to roundtrip.
See the "attribute selector" section of "Serializing Selectors" here:
https://drafts.csswg.org/cssom/#serializing-selectors
CSSStyleRule.selectorText is specified here:
https://drafts.csswg.org/cssom/#dom-cssstylerule-selectortext
To simplify adding additional data to `ParserContext`, this moves test usages to
a few shared locations, instead of being spread across many tests.
MozReview-Commit-ID: 1OahV797eq
