This feature is mainly for Khmer: The idea is to avoid a clash
between the top of subscript glyphs and the bottom of normal
baseline glyphs.
This only works for character clusters mapped to multiple glyphs.
* src/autofit/afblue.dat: Add subscript top blue zone for Khmer.
* src/autofit/afblue.hin (AF_BLUE_PROPERTY_LATIN_SUB_TOP): New
macro.
* src/autofit/afblue.c, src/autofit/afblue.h: Regenerated.
* src/autofit/aflatin.h (AF_LATIN_IS_SUB_TOP_BLUE,
AF_LATIN_BLUE_SUB_TOP): New macros.
* src/autofit/aflatin.c (af_latin_metrics_init_blues): Handle new
blue zone property.
Update tracing messages.
(af_latin_metrics_scale_dim): Handle new blue zone property.
(af_latin_hints_compute_blue_edges): Updated.
0164d934b6