Remove FontDescriptionChangeScope, and let FontBuilder partially apply values.

Source/platform/fonts/FontDescription.h

Index: Source/platform/fonts/FontDescription.h
diff --git a/Source/platform/fonts/FontDescription.h b/Source/platform/fonts/FontDescription.h
index f736b52867fcd744493a643c250d152edcd8f4c6..f0f9f84cf370d61c09e6498acd325c62090e403b 100644
--- a/Source/platform/fonts/FontDescription.h
+++ b/Source/platform/fonts/FontDescription.h
@@ -89,11 +89,11 @@ public:
     bool operator!=(const FontDescription& other) const { return !(*this == other); }
 
     struct VariantLigatures {
-        VariantLigatures()
-            : common(NormalLigaturesState)
-            , discretionary(NormalLigaturesState)
-            , historical(NormalLigaturesState)
-            , contextual(NormalLigaturesState)
+        VariantLigatures(LigaturesState state = NormalLigaturesState)
+            : common(state)
+            , discretionary(state)
+            , historical(state)
+            , contextual(state)
         {
         }