Remove secret wireframe mode from drawVertices

Now, drawing vertices without colors or a shader simply fills with the
paint color, like anyone would expect.

Bug: skia:9984
Change-Id: I9f7cf72f89948756b9c2c6e055a11c6b64fc22ff
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/282043
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
4 files changed