Formalize edge-aa interaction with GrAA

With this formalization, the edge-AA APIs in GrRTC can distinguish
between tiling cases and regular drawing cases implemented using
kNone or kAll for the AA flags. This means fillRectToRect can be
implemented in terms of fillRectWithEdgeAA.

It also means the drawTexture cases will properly handle
isolated draws and tiled draws when drawing into MSAA.

Bug: skia:
Change-Id: I248dd001919228a958cf84b6bc91363b58b72c0b
Reviewed-on: https://skia-review.googlesource.com/c/192023
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
8 files changed