remove some legacy flags for g3

BUG=skia:

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=3672

Change-Id: Idc30ed9d367026352747619580bf12da7aa9ffe5
Reviewed-on: https://skia-review.googlesource.com/3672
Reviewed-by: Ben Wagner <benjaminwagner@google.com>
Commit-Queue: Mike Reed <reed@google.com>
diff --git a/public.bzl b/public.bzl
index 1c6d2e5..4655a64 100644
--- a/public.bzl
+++ b/public.bzl
@@ -601,17 +601,13 @@
     # Staging flags for API changes
     "SK_SUPPORT_LEGACY_ACCESSBITMAP",
     "SK_SUPPORT_LEGACY_ARITHMETICMODE",
-    "SK_SUPPORT_LEGACY_COLORFILTER_PTR",
-    "SK_SUPPORT_LEGACY_CREATESHADER_PTR",
     "SK_SUPPORT_LEGACY_IMAGEFACTORY",
-    "SK_SUPPORT_LEGACY_IMAGEFILTER_PTR",
     "SK_SUPPORT_LEGACY_MASKFILTER_PTR",
     "SK_SUPPORT_LEGACY_MINOR_EFFECT_PTR",
     "SK_SUPPORT_LEGACY_NEW_SURFACE_API",
     "SK_SUPPORT_LEGACY_PATHEFFECT_PTR",
     "SK_SUPPORT_LEGACY_PICTURE_PTR",
     "SK_SUPPORT_LEGACY_TYPEFACE_PTR",
-    "SK_SUPPORT_LEGACY_XFERMODE_PTR",
     "SK_SUPPORT_LEGACY_PICTUREINSTALLPIXELREF",
     "SK_SUPPORT_LEGACY_STREAM_DATA",
     "SK_SUPPORT_LEGACY_CLIP_REGIONOPS",