hb-ft transform issue

[behdad]

When fixing bitmap fonts with hb-ft, I made advance (and other) functions apply the FT_Face transform. Two issues with that:

1. It was a breaking change for clients. Caused: Scaling change #3788

2. As noted in that issue, this is also broken because GPOS doesn't take that transform into consideration.

The correct fix is to NOT do this; instead have hb-view apply the transform.

[behdad]

Umm. This is hard to fix.

[behdad]

I came up with a patch to conditionally apply the FT transform; only when we created the face.