Fix reading and writing format 13 cmap tables

Fix reading and writing format 13 cmap tables

* language is a 32-bit field when reading
* fix table length calculation when writing

See https://cloudup.com/cl1gWiyp7gS to download an example font that
fails sanitization before this change, but passes afterward.

R=yusukes@chromium.org

[devongovett, 2014-09-28 05:31:26]

devongovett@gmail.com changed reviewers:
+ behdad@chromium.org

[devongovett, 2014-09-28 05:32:39]

devongovett@gmail.com changed reviewers:
+ ksakamoto@chromium.org

[devongovett, 2014-10-13 01:05:28]

Bump.

[behdad_google, 2014-10-13 23:31:19]

behdad@google.com changed reviewers:
+ behdad@google.com

[behdad_google, 2014-10-13 23:31:19]

lgtm

Note that these are fixed in the github fork already.  We should switch Chrome
ASAP.

[Kunihiko Sakamoto, 2014-10-16 08:01:03]

lgtm

Thanks. Committed as r117.
https://code.google.com/p/ots/source/detail?r=117