Remove unneeded test, and support code

The SkRemoteGlyphCache_ReWriteGlyph checked that glyphs of
desparation were not overwritten by glyphs coming from the
Renderer. Since the search of desparation is no longer, this
test is not needed.

In addition:
* Remove unused call prepareForDrawingPathsCPU.
* Cleanup some comments

Change-Id: I1fbc3f84363c9093f5301985e8052f49bbb9356e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/270996
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Herb Derby <herb@google.com>
5 files changed