Disable subpixel text on linux systems with full_hinting

Source/platform/fonts/linux/FontPlatformDataLinuxHarfBuzz.cpp

Index: Source/platform/fonts/linux/FontPlatformDataLinuxHarfBuzz.cpp
diff --git a/Source/platform/fonts/linux/FontPlatformDataLinuxHarfBuzz.cpp b/Source/platform/fonts/linux/FontPlatformDataLinuxHarfBuzz.cpp
index 0ffd78336b104008cdee59867b17df3d2b02ff98..c05fa20be983c736f2856d32753008c565510dbc 100644
--- a/Source/platform/fonts/linux/FontPlatformDataLinuxHarfBuzz.cpp
+++ b/Source/platform/fonts/linux/FontPlatformDataLinuxHarfBuzz.cpp
@@ -82,7 +82,9 @@ void FontPlatformData::setupPaint(SkPaint* paint, GraphicsContext*) const
         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);