Fix underline position and thickness calculation

Source/platform/fonts/skia/SimpleFontDataSkia.cpp

Index: Source/platform/fonts/skia/SimpleFontDataSkia.cpp
diff --git a/Source/platform/fonts/skia/SimpleFontDataSkia.cpp b/Source/platform/fonts/skia/SimpleFontDataSkia.cpp
index 2ac44c3768002d951d47fee60d77e94d2992863e..0e20e86668f63c57737ae24ff42c47bdd1641456 100644
--- a/Source/platform/fonts/skia/SimpleFontDataSkia.cpp
+++ b/Source/platform/fonts/skia/SimpleFontDataSkia.cpp
@@ -131,11 +131,12 @@ void SimpleFontData::platformInit()
     m_fontMetrics.setLineGap(lineGap);
     m_fontMetrics.setLineSpacing(lroundf(ascent) + lroundf(descent) + lroundf(lineGap));
 
-    float underlineThickness = SkScalarToFloat(metrics.fUnderlineThickness);
-    m_fontMetrics.setUnderlineThickness(underlineThickness);
-
-    float underlinePosition = SkScalarToFloat(metrics.fUnderlinePosition);
-    m_fontMetrics.setUnderlineThickness(underlinePosition);
+    SkScalar underlineThickness, underlinePosition;
+    if (metrics.hasUnderlineThickness(&underlineThickness)
+        && metrics.hasUnderlinePosition(&underlinePosition)) {
+        m_fontMetrics.setUnderlineThickness(SkScalarToFloat(underlineThickness));
+        m_fontMetrics.setUnderlinePosition(SkScalarToFloat(-underlinePosition));
+    }
 
     if (platformData().orientation() == Vertical && !isTextOrientationFallback()) {
         static const uint32_t vheaTag = SkSetFourByteTag('v', 'h', 'e', 'a');