Fix GrDrawContextPriv::stencilRect

Updates stencilRect to call drawNonAAFilledRect instead of
drawFilledRect. drawFilledRect can use coverage AA, which isn't
appropriate for stencil draws. Also modifies drawNonAAFilledRect to
take a "useHWAA" argument instead of trying to deduce whether it
should be used.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2187583002

Review-Url: https://codereview.chromium.org/2187583002
2 files changed