CanOverflow -> ClampIfNeeded

Centralize the clamping in ClampIfNeeded, and switch it to clamp_1.

Change-Id: I056ac029d3ddc81e3f0f194f2b9c9924cad4caae
Reviewed-on: https://skia-review.googlesource.com/19401
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Mike Reed <reed@google.com>
5 files changed