when we disable lcd for impl reasons, add kGenA8 to document the original intent

src/gpu/SkGpuDevice.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkGpuDevice.h"
 
 #include "effects/GrBicubicEffect.h"
@@ skipping 1747 matching lines @@
     }
 
     if (paint.getShader() ||
         paint.getXfermode() || // unless its srcover
         paint.getMaskFilter() ||
         paint.getRasterizer() ||
         paint.getColorFilter() ||
         paint.getPathEffect() ||
         paint.isFakeBoldText() ||
         paint.getStyle() != SkPaint::kFill_Style) {
-        // turn off lcd
+        // turn off lcd, but turn on kGenA8
         flags->fFlags = paint.getFlags() & ~SkPaint::kLCDRenderText_Flag;
-        flags->fHinting = paint.getHinting();
+        flags->fFlags |= SkPaint::kGenA8FromLCD_Flag;
         return true;
     }
     // we're cool with the paint as is
     return false;
 }
 
 void SkGpuDevice::flush() {
     DO_DEFERRED_CLEAR();
     fContext->resolveRenderTarget(fRenderTarget);
 }
@@ skipping 161 matching lines @@
     GrLayerHoister::UnlockLayers(fContext->getLayerCache(), picture);
 
     return true;
 }
 
 SkImageFilter::Cache* SkGpuDevice::getImageFilterCache() {
     // We always return a transient cache, so it is freed after each
     // filter traversal.
     return SkImageFilter::Cache::Create(kDefaultImageFilterCacheSize);
 }