Less rejecting, more sanitizing

[behdad]

[This report is motivated by discussion in https://bugzilla.mozilla.org/show_bug.cgi?id=964696 ]

When OTS was first born, it was to sanitize tables, ie. read them, and write back correct tables. Now that's a very hard task for many tables, so over time it started outright rejecting tables fairly broadly. I think we should try to address that. For example, the cmap table issue discussed in the above URL can easily be fixed by OTS instead of rejecting the font.

[khaledhosny]

I was thinking about this when looking into some other issues as well. Many things that we reject tables for can be simply fixed in the serialized table, the issue is that for most of the tables I looked into we have no code to construct new table data i.e. we either accept it as is or outright drop it, so that will be a bit of work.

[behdad]

Yeah, understood.

[HinTak]

And sometimes, it may not be obvious in which way one should "fix" a broken table, especially automating such a process. rejecting any broken-ness is certainly easier to do.