SkAdvancedTypefaceMetrics: simplify more

Change-Id: I80c28c50aa96c28181d2fef13daad4a80ec91a12
Reviewed-on: https://skia-review.googlesource.com/120160
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Hal Canary <halcanary@google.com>
7 files changed