[whatwg] Invalid values of dir attribute causing change in appearance?

[L. David Baron]

http://www.whatwg.org/specs/web-apps/current-work/multipage/rendering.html#bidirectional-text
specifies that UA style sheets should have the rule:
  [dir] { unicode-bidi: embed; }

This implies that invalid values of the dir attribute should cause a
change in presentation.  This seems wrong to me, on the general
principle that invalid values of attributes should be ignored.
(Though perhaps this isn't a general principle that we're following
anymore?  I rather thought it was, though.)

I tend to think that only the known values of the dir attribute
should cause the unicode-bidi:embed styling.

(I'm asking since this has been tested and bugs filed:
https://bugzilla.mozilla.org/show_bug.cgi?id=713621 .)

-David

-- 
𝄞   L. David Baron                         http://dbaron.org/   𝄂
𝄢   Mozilla                           http://www.mozilla.org/   𝄂