252530 - Create preshint.css to load presentational hint rules at preshint level in cascade

Status: NEW

(Core :: CSS Parsing and Computation, defect)

Description

[fantasai]

We need a stylesheet to load rules like those in bug 43178 at the preshint level
in nsStyleSet. Boris says this will involve adding APIs to load the sheet as
well as removing some asserts that check for an absence of CSS sheets in that
level of the cascade.

Comment 1

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Should this rules be ahead of or behind the rules from nsHTMLStylesheet?  Pick
one, and create another level of the cascade appropriately.  (I'm planning to
change things to ensure that there's only one rule processor per level.  We have
no mechanism to cascade the rules from CSS and non-CSS stylesheets together, nor
should we need one.)

Comment 2

[fantasai]

Once bug 43178 is fixed, this will depend on 84307; otherwise the table 'rules' rules will break quirks mode border handling when we start loading 43178's style sheet at preshint level.

Comment 3

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Note that http://www.w3.org/TR/CSS21/cascade.html#preshint has a list of exactly which rules should be in preshint.css:  anything to do with HTML attributes not on the list given there.

Additionally, there are a bunch of attributes in the list given that we handle through attribute mapping code (e.g., lang, dir, colspan, rowspan, span).  We'd need to separate the attribute mapping for those attributes so that it happens at the user-agent level.