Fix F16 raster text masks. We don't want fake gamma in that case.

src/core/SkDraw.cpp

Index: src/core/SkDraw.cpp
diff --git a/src/core/SkDraw.cpp b/src/core/SkDraw.cpp
index 7787a28249479430c03d78fb31150f04be0cc7a5..ce4c4081f22d1ae00dfc1ba82a0b7b8765f1aad8 100644
--- a/src/core/SkDraw.cpp
+++ b/src/core/SkDraw.cpp
@@ -1585,8 +1585,7 @@ private:
 
 uint32_t SkDraw::scalerContextFlags() const {
     uint32_t flags = SkPaint::kBoostContrast_ScalerContextFlag;
-    // TODO: how should we handle non-srgb, non-linear gamma?
-    if (!fDevice->imageInfo().gammaCloseToSRGB()) {
+    if (!SkImageInfoIsGammaCorrect(fDevice->imageInfo())) {
         flags |= SkPaint::kFakeGamma_ScalerContextFlag;
     }
     return flags;