remove forceW system

The SkAtlasTextTarget forced W for drawing using 3D vertices. Since it
is gone, the force W system is not needed.

Change-Id: Ic70b2f9aa5fd845dcfa7b06b5905afeb72f96441
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/294600
Commit-Queue: Herb Derby <herb@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
8 files changed