TrueType kerning is broken

[brawer]

According to git bisect, commit a519588 has broken test case KERN-1 in text-rendering-tests. This test font has a TrueType kern table. Before that commit, HarfBuzz had been producing the expected output:

$ util/hb-view test/shaping/data/text-rendering-tests/fonts/TestKERNOne.otf ıTuTuTı -o KERN.png

Since commit a519588, HarfBuzz seems to ignore the font’s kern table:

[brawer]

Interestingly, the HarfBuzz test suite didn’t notice this breakage, even though it runs the test cases KERN-1 and KERN-2 upon make check.

$ git checkout 11703afce6cebbb4c5e7cdea59ca59a1787608b8  # a broken version
$ make distclean ; sh autogen.sh ; make check
[...]
make[6]: Entering directory '/harfbuzz/test/shaping/data/text-rendering-tests'
PASS: tests/AVAR-1.tests
[...]
PASS: tests/KERN-1.tests
PASS: tests/KERN-2.tests
[...]
SKIP: tests/basics.tests
SKIP: tests/full-font.tests
SKIP: tests/japanese.tests
============================================================================
Testsuite summary for HarfBuzz 1.9.0
============================================================================
# TOTAL: 3
# PASS:  0
# SKIP:  3
# XFAIL: 0
# FAIL:  0
# XPASS: 0
# ERROR: 0

[behdad]

That commit was broken. Needed a03850a to fix.

But this doesn't make sense. Let me check.