This makes test suite happy again (at 44) while fixing the sequences
we were fixing, which were the following with KhmerUI.ttf:
U+1789,U+17BC
U+1789,U+17D2,U+1789
U+1789,U+17D2,U+1789,U+17BC
Fixes rest of https://github.com/harfbuzz/harfbuzz/issues/974
Khmer spec has only one reordering phase, and only simple prebase
matra and Coeng-Ro reordering. Implement that. Specifically,
this was done to address recognizing different orders of the matra
and Coeng-Ro sequence. That said, some combinations are now
reordered differently from Uniscribe. Not clear if that's intended
or a bug in Uniscribe. The following two sequences render the same
in Uniscribe whereas we reorder them differently:
U+17A0,U+17D2,U+179A,U+17C2
U+17A0,U+17C2,U+17D2,U+179A
For that reason, our test suite numbers regressed slightly. Used
to be at 34 for fails, now at:
KHMER: 299080 out of 299124 tests passed. 44 failed (0.0147096%)
But generally a good change, and removed lots of code.
Fixes https://github.com/harfbuzz/harfbuzz/issues/1026
Towards fixing https://github.com/harfbuzz/harfbuzz/issues/667
The Khmer spec is different enough from other Indic ones to require
its own grammar.
No change in functionality. Test numbers are:
BENGALI: 353725 out of 354188 tests passed. 463 failed (0.130722%)
DEVANAGARI: 707307 out of 707394 tests passed. 87 failed (0.0122987%)
GUJARATI: 366355 out of 366457 tests passed. 102 failed (0.0278341%)
GURMUKHI: 60729 out of 60747 tests passed. 18 failed (0.0296311%)
KANNADA: 951300 out of 951913 tests passed. 613 failed (0.0643966%)
KHMER: 299071 out of 299124 tests passed. 53 failed (0.0177184%)
MALAYALAM: 1048136 out of 1048334 tests passed. 198 failed (0.0188871%)
ORIYA: 42320 out of 42329 tests passed. 9 failed (0.021262%)
SINHALA: 271662 out of 271847 tests passed. 185 failed (0.068053%)
TAMIL: 1091754 out of 1091754 tests passed. 0 failed (0%)
TELUGU: 970555 out of 970573 tests passed. 18 failed (0.00185457%)