Remove gpu buffer reads from default path renderer.
Remove gpu buffer reads from default path renderer.

I don't actually expect to see much perf gain from this one because the
reads happen when we've run out of space in our vertex buffer and need
a new allocation. So they happen pretty rarely.

Change-Id: Iabe2e7cebf363659180409075a1a7fc6c03d0a22
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/364618
Commit-Queue: Greg Daniel <39df0a804564ccb6cf75f18db79653821f37c1c5@google.com>
Reviewed-by: Chris Dalton <ef7fc3a08ada7d31f16e9a18b5f3c728256e041e@google.com>

google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,google/skia,google/skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,google/skia,aosp-mirror/platform_external_skia,google/skia,google/skia,aosp-mirror/platform_external_skia