Intent to unship: Deprecated MathML style attributes

[Frédéric Wang]

Hi

In [1], I mentioned the intent to unship <math>'s mode attribute. In bug
1548524, I'll intend to unship the remaining attributes deprecated in
MathML3: fontfamily, fontweight, fontstyle, fontsize, color and background.

Actually, these have been deprecated since MathML2 [2] (released 16
years ago) and we have been sending deprecation warnings since Mozilla
20 (released 6 years ago). The MathML CG agreed to removed them from
MathML Core [3] and Igalia does not plan to implement them in Chromium.

Contrary to the mode attribute, these attributes are also implemented in
WebKit [4] and we got bug reports about some of them in the past [5].
Hence, it makes sense to be a bit more careful. For now they will only
be disabled in nightly and use counters to determine how much they are used.

[1]
https://groups.google.com/forum/#!topic/mozilla.dev.platform/lZUF2Z9jOh4/discussion
[2] https://www.w3.org/TR/MathML2/chapter3.html#presm.deprecatt
[3] https://github.com/mathml-refresh/mathml/issues/5
[4]
https://trac.webkit.org/browser/webkit/trunk/Source/WebCore/mathml/MathMLElement.cpp#L96
[5] e.g. https://bugzilla.mozilla.org/show_bug.cgi?id=1027354

--
Frédéric Wang