remove dead code around SK_SUPPORT_LEGACY_TEXTBLOB_SERIAL_API

Bug: skia:
Change-Id: Ifcf6054871d907efeb2fcf2815bc4c25671525b6
Reviewed-on: https://skia-review.googlesource.com/25944
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>
2 files changed