Enable delta AA by default
Enable delta AA by default

The earlier CL doesn't change the flag definition so it's not
turned on yet.

Bug: skia:
Change-Id: Id278ae5fc27d703ab7f6628bed95093d32cd7d0b
TBR: b79721911748ec6c55b678eeb430a3e9a13a3958@chromium.org
Reviewed-on: https://skia-review.googlesource.com/28161
Commit-Queue: Yuqian Li <5537666080209cb36918c342659e07eb122af24c@google.com>
Reviewed-by: Yuqian Li <5537666080209cb36918c342659e07eb122af24c@google.com>

HalCanary/skia-hc,rubenvb/skia,google/skia,aosp-mirror/platform_external_skia,google/skia,rubenvb/skia,aosp-mirror/platform_external_skia,rubenvb/skia,rubenvb/skia,Hikari-no-Tenshi/android_external_skia,google/skia,google/skia,rubenvb/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,HalCanary/skia-hc,Hikari-no-Tenshi/android_external_skia,Hikari-no-Tenshi/android_external_skia,rubenvb/skia,HalCanary/skia-hc,Hikari-no-Tenshi/android_external_skia,Hikari-no-Tenshi/android_external_skia,aosp-mirror/platform_external_skia,google/skia,Hikari-no-Tenshi/android_external_skia,aosp-mirror/platform_external_skia,rubenvb/skia,HalCanary/skia-hc,google/skia,google/skia,google/skia,rubenvb/skia,Hikari-no-Tenshi/android_external_skia,aosp-mirror/platform_external_skia,HalCanary/skia-hc,HalCanary/skia-hc,HalCanary/skia-hc,google/skia,Hikari-no-Tenshi/android_external_skia,aosp-mirror/platform_external_skia,rubenvb/skia,aosp-mirror/platform_external_skia,HalCanary/skia-hc,rubenvb/skia,HalCanary/skia-hc,HalCanary/skia-hc