Benchmark rotated rect with AA/noAA

Using this benchmark, we verify that AA is about 4x slower than noAA in
path_fill_big_rotated_rect. This is what I aim to improve in the next
CL.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2087453003

Review-Url: https://codereview.chromium.org/2087453003
1 file changed