[HarfBuzz] Wrong GDEF class in timesi.ttf on Win7

[Jonathan Kew]

On 24/2/16 02:25, Behdad Esfahbod wrote:
> Hi Jonathan,
>
> As you probably know, I changed mark zeroing from BY_UNICODE_LATE to
> BY_GDEF_LATE in HarfBuzz.  So far I only got a bug report about Cantarell
> breaking, which was fixed in the font's GDEF table.
>
> Today, Dominik and I noticed that Times New Roman Italic on Windows 7 has
> wrong GDEF class for ASCII double-quote, and as such, we now zero its advance
> width.  The bug is not present in Windows XP or Windows 8 on.  It also happens
> to be present on the OpenType Times New Roman Italic on OS X, but that is
> superseded by a non-OpenType version of the font.
>
> Even with the broken font, CoreText does not show the bad rendering, whereas,
> in my testing, Uniscribe from Windows 7 does.
>
> Given that Windows 7 still has the largest market share across PCs, I feel
> like we cannot ignore this.  I assume IE probably does not expose this bug
> because they don't process OpenType features for Latin?  Can someone test on
> Windows 7?

I don't have a test system handy just now, but I believe you're correct.

>
> I'm not sure how to proceed forward.  IIRC we have had also observed one Latin
> glyph with wrong GDEF back a few years ago, in Georgia or some other font on
> Windows.  That should be in mozilla bug tracker somewhere.

See https://bugzilla.mozilla.org/show_bug.cgi?id=589682 for the Times 
New Roman Italic GDEF bug. (We added a hack in Gecko to ignore the GDEF 
for that particular font.)

JK