For font weights >= 600, create bold system fonts.

Source/platform/fonts/win/FontCacheSkiaWin.cpp

Index: Source/platform/fonts/win/FontCacheSkiaWin.cpp
diff --git a/Source/platform/fonts/win/FontCacheSkiaWin.cpp b/Source/platform/fonts/win/FontCacheSkiaWin.cpp
index 1913f840de7888b590459dc06ffc8ee32d8341b8..6b408da51113c2275768e920491b7774b9319597 100644
--- a/Source/platform/fonts/win/FontCacheSkiaWin.cpp
+++ b/Source/platform/fonts/win/FontCacheSkiaWin.cpp
@@ -224,7 +224,7 @@ FontPlatformData* FontCache::createFontPlatformData(const FontDescription& fontD
     FontPlatformData* result = new FontPlatformData(tf,
         name.data(),
         fontSize,
-        fontDescription.weight() >= FontWeightBold && !tf->isBold() || fontDescription.isSyntheticBold(),
+        fontDescription.weight() >= FontWeight600 && !tf->isBold() || fontDescription.isSyntheticBold(),
         fontDescription.style() == FontStyleItalic && !tf->isItalic() || fontDescription.isSyntheticItalic(),
         fontDescription.orientation(),
         s_useSubpixelPositioning);