Enable Skia's integral-translate bilerp optimization

Remove SK_SUPPORT_LEGACY_BILERP.

Change-Id: I38b9154cdc1e2ee064158af9d92d08d1c6297458
Reviewed-on: https://chromium-review.googlesource.com/575675
Commit-Queue: Florin Malita <fmalita@chromium.org>
Reviewed-by: Mike Klein <mtklein@chromium.org>
Cr-Commit-Position: refs/heads/master@{#487507}

skia/config/SkUserConfig.h

@@ -195,10 +195,6 @@ SK_API void SkDebugf_FileLine(const char* file, int line, bool fatal,
 #define SK_SUPPORT_LEGACY_HQ_SCALER
 #endif
 
-#ifndef SK_SUPPORT_LEGACY_BILERP
-#define SK_SUPPORT_LEGACY_BILERP
-#endif
-
 // Workaround for poor anisotropic mipmap quality,
 // pending Skia ripmap support.
 // (https://bugs.chromium.org/p/skia/issues/detail?id=4863)