Remove lang parameter from TextBlob alloc methods.

The 'lang' was never stored or used, so this makes no current practical
difference. The original intent was to be able to specify a language so
that it could be emitted as a 'Lang' override in the 'ActualText' when
generating a PDF. However, due to the way 'ActualText' is generally used
this would be impractical. If there is ever a desire to mark up sections
of the PDF with a specific language it would be better handled in a
different way.

Change-Id: Id63596190235fc45ce17249b9b578b6f9b838b2b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/375060
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
7 files changed