Through the Arabic shaper.  It's similar to Mongolian.

Patch from Jonathan Kew.

Part of fixing:

Mozilla Bug 801410 - avoid inserting dotted-circle for run-initial
Unicode combining characters in "simple" scripts such as Latin

https://bugzilla.mozilla.org/show_bug.cgi?id=801410

We should make it clear that we don't want output buffer in this case,
otherwise buffer->backtrack_len() would be wrong.

That's what the spec says, and what Uniscribe does.

This sequence: U+120B,U+135F,U+120B with the Nyala font from Win7
exposes a GPOS bug in Uniscribe, in that the positioned mark is wrongly
moved as a result a following kern.

This is the one "failure" in the Ethiopic test suite :-).

ETHIOPIC: 118900 out of 118901 tests passed. 1 failed (0.000841036%)

The logic for pre-base reordering follows the left matra logic.
We had an exception for Malayalam/Tamil in the left matra repositioning
which was not reflected in pre-base reordering.

Malayalam failures down from 337 to 323.

BENGALI: 353996 out of 354285 tests passed. 289 failed (0.0815727%)
DEVANAGARI: 707339 out of 707394 tests passed. 55 failed (0.00777502%)
GUJARATI: 366489 out of 366506 tests passed. 17 failed (0.0046384%)
GURMUKHI: 60769 out of 60809 tests passed. 40 failed (0.0657797%)
KANNADA: 951086 out of 951913 tests passed. 827 failed (0.0868777%)
KHMER: 299106 out of 299124 tests passed. 18 failed (0.00601757%)
LAO: 53611 out of 53644 tests passed. 33 failed (0.0615167%)
MALAYALAM: 1048011 out of 1048334 tests passed. 323 failed (0.0308108%)
ORIYA: 42320 out of 42329 tests passed. 9 failed (0.021262%)
SINHALA: 271726 out of 271847 tests passed. 121 failed (0.0445103%)
TAMIL: 1091837 out of 1091837 tests passed. 0 failed (0%)
TELUGU: 970558 out of 970573 tests passed. 15 failed (0.00154548%)
TIBETAN: 208469 out of 208469 tests passed. 0 failed (0%)

I typically don't like including generating files in tree.  But like to
make an exception for this, since this forms the canonical list of
options one would need to go through when building with alternative
build systems.

Was causing invalid realloc()s.

Incidentally, this makes it not crash with icu-le-hb anymore...
I'm not smart / stupid enough to spend two more days debugging C++
linking issues, and this is ABI-stable at least.

That's really the logic desired.  Except that MONGOLIAN VOWEL SEPARATOR
is not default_ignorable but it really should be.  Reported to Unicode.

Based on suggestion from Konstantin Ritt.

Broke it when merged cmap mapping and normalizer.  Ouch!

- Unicode 6.2.0 goodness,
- Unassigned codepoints now have correct properties.  Passes test suite.

https://github.com/grigorig/ucdn

Now that we have pthread detection in configure, we don't need Glib
anymore.  Glib will only be a Unicode data provider.

If the first char in the run is a combining mark, but there is text
before the run, don't insert dottedcircle.

Part of addressing:
https://bugzilla.redhat.com/show_bug.cgi?id=858736

Now we respect Arabic joining across runs.

To be used for a variety of purposes.  We save up to five characters
in each direction.  No public API changes, everything is taken care
of already.  All clients need to do is to call hb_buffer_add_utf* with
the full text + segment info (or at least some context) instead of
just passing in the segment.

Various operations (hb_buffer_reset, hb_buffer_set_length,
hb_buffer_add*) automatically reset the relevant contexts.