Some scissor state cleanup.

Separate flushing the enablement of scissor from the rect in GrGLGpu.

Move GrPipeline::ScissorState to a global enum and use more broadly.
Rename to GrScissorTest to avoid name conflict with existing
GrScissorState.

Change-Id: Ib32160b3300bc12de2d2e1761d152fd1bba8b683
Reviewed-on: https://skia-review.googlesource.com/137395
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Chris Dalton <csmartdalton@google.com>
23 files changed