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

src/core/SkDraw.cpp

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #define __STDC_LIMIT_MACROS
 
 #include "SkDraw.h"
 #include "SkBlitter.h"
@@ skipping 1567 matching lines @@
     const SkRegion* const fClip;
     const SkDraw&         fDraw;
     const SkPaint&        fPaint;
     const SkIRect         fClipBounds;
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
 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;
 }
 
 void SkDraw::drawText(const char text[], size_t byteLength,
                       SkScalar x, SkScalar y, const SkPaint& paint) const {
     SkASSERT(byteLength == 0 || text != nullptr);
 
     SkDEBUGCODE(this->validate();)
@@ skipping 507 matching lines @@
         mask->fImage = SkMask::AllocImage(size);
         memset(mask->fImage, 0, mask->computeImageSize());
     }
 
     if (SkMask::kJustComputeBounds_CreateMode != mode) {
         draw_into_mask(*mask, devPath, style);
     }
 
     return true;
 }