OpenType layout tables differ between OTF and TTF versions

[jfkthame]

Comparing the GPOS tables in FiraSans 4.101, there are a number of differences that will result in unexpected discrepancies in behavior between the two font formats.

Testcase: http://people.mozilla.org/~jkew/tests/Fira4101/FiraTest.html

This example displays the same character sequences using both the OTF and TTF versions of the font. Note the different results!

[patrykdesign]

@carrois can you please comment? wouldn't want to push in v.4.101 yet if this is infact a bug.

[jfkthame]

This issue is still present in the most recent Fira 4.102 files.

Testcase (with updated fonts as of today): http://people.mozilla.org/~jkew/tests/Fira4102/FiraTest.html

[jfkthame]

Still broken in 4.103 today. Note that issue 85 shows a real-world example where the mismatch in OpenType support means the OTF release is broken even though the TTF version works.

[jfkthame]

Note that this issue also affects Fira Mono -- there are discrepancies in the OpenType layout behavior between OTF and TTF versions. Because of the smaller character set, there aren't as many examples to be found, but U+037A and U+1FBE are a couple of (Greek) characters that show behavioral differences.

[jfkthame]

In the Fira Mono fonts from #56 (comment), there is no longer any discrepancy between the OpenType features in OTF and TTF files, afaics.

@carrois @schriftgestalt We still need to check whether this is resolved for Fira Sans, with its richer character set and more extensive OpenType tables.

[patrykdesign]

@jfkthame this should be fixed with 4.105 now, can you confirm?
I can confirm 4.105 fixed #85 which seemed related.
Thanks!

[patrykdesign]

Tested with Fira 4.105 using @jfkthame test v.4.104 test file and looks like its fixed now.