Revert of Modifying TextBlobCacheTest to use SkRandomScalerContext (patchset #3 id:40001 of https://codereview.chromium.org/1266003002/)

Reason for revert:
breaking android

Original issue's description:
> Modifying TextBlobCacheTest to use SkRandomScalerContext
>
> BUG=skia:
>
> Committed: https://skia.googlesource.com/skia/+/adcdca86ce425cf8c28bfad311cef028df756ee8

TBR=bungeman@google.com,bsalomon@google.com,joshualitt@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Review URL: https://codereview.chromium.org/1267623004
7 files changed