Remove legacy mask blur code.

This was flag flipped about last year in the chrome code, and
flag flipped about three weeks ago in Android.

All the *_LEGACY_*BLUR flags are gone.

Change-Id: I046f3a040ccbf12ff3a810c41b02131095df3368
Reviewed-on: https://skia-review.googlesource.com/96001
Reviewed-by: Mike Klein <mtklein@chromium.org>
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Herb Derby <herb@google.com>
2 files changed