Move scaler context fallback to GDI

The GDI Typeface is the only one that can fail to make a
scaler context. Move all the logic to the GDI specific code.

Change-Id: I50a0a58529bb44625068244e6ae27e54bccd9f67
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/269913
Commit-Queue: Herb Derby <herb@google.com>
Reviewed-by: Herb Derby <herb@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
12 files changed