Revert "hide nested hinting enum"

This reverts commit fbebecee0eb99338e1b08422842aba6ab724e243.

Reason for revert: need staging guard for flutter

Original change's description:
> hide nested hinting enum
> 
> Bug: skia:2664
> Bug: skia:8527
> Change-Id: I8f4b832d5524fb792bcc608d6bd515229881b048
> Reviewed-on: https://skia-review.googlesource.com/c/168270
> Commit-Queue: Mike Reed <reed@google.com>
> Reviewed-by: Florin Malita <fmalita@chromium.org>

TBR=fmalita@chromium.org,reed@google.com

Change-Id: I19496daa059932574f36ac47061068a81d5524c3
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:2664, skia:8527
Reviewed-on: https://skia-review.googlesource.com/c/169344
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>
28 files changed