Disable subpixel text on linux systems with full_hinting

Source/platform/fonts/linux/FontPlatformDataLinuxHarfBuzz.cpp

 /*
  * Copyright (c) 2006, 2007, 2008, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 64 matching lines @@
 void FontPlatformData::setupPaint(SkPaint* paint, GraphicsContext*) const
 {
     paint->setAntiAlias(m_style.useAntiAlias);
     paint->setHinting(static_cast<SkPaint::Hinting>(m_style.hintStyle));
     paint->setEmbeddedBitmapText(m_style.useBitmaps);
     paint->setAutohinted(m_style.useAutoHint);
     if (m_style.useAntiAlias)
         paint->setLCDRenderText(m_style.useSubpixelRendering);
 
     // TestRunner specifically toggles the subpixel positioning flag.
-    if (RuntimeEnabledFeatures::subpixelFontScalingEnabled() && !isRunningLayoutTest())
+    if (RuntimeEnabledFeatures::subpixelFontScalingEnabled()
+        && paint->getHinting() != SkPaint::kFull_Hinting
+        && !isRunningLayoutTest())
         paint->setSubpixelText(true);
     else
         paint->setSubpixelText(m_style.useSubpixelPositioning);
 
     const float ts = m_textSize >= 0 ? m_textSize : 12;
     paint->setTextSize(SkFloatToScalar(ts));
     paint->setTypeface(m_typeface.get());
     paint->setFakeBoldText(m_syntheticBold);
     paint->setTextSkewX(m_syntheticItalic ? -SK_Scalar1 / 4 : 0);
 }
@@ skipping 44 matching lines @@
         || isRunningLayoutTest())
         m_style.useSubpixelPositioning = useSkiaSubpixelPositioning;
 }
 
 bool FontPlatformData::defaultUseSubpixelPositioning()
 {
     return FontDescription::subpixelPositioning();
 }
 
 } // namespace WebCore