Use StyleBuilderConverter for text-decoration(-line).

Source/core/css/resolver/StyleBuilderConverter.h

Index: Source/core/css/resolver/StyleBuilderConverter.h
diff --git a/Source/core/css/resolver/StyleBuilderConverter.h b/Source/core/css/resolver/StyleBuilderConverter.h
index d011ddcb029f22bbea6c67db6e2666a6d8e86339..3734e5c0e86f1164a557dde83fadc9044beafdf5 100644
--- a/Source/core/css/resolver/StyleBuilderConverter.h
+++ b/Source/core/css/resolver/StyleBuilderConverter.h
@@ -46,6 +46,7 @@ public:
     static AtomicString convertFragmentIdentifier(StyleResolverState&, CSSValue*);
     static Color convertColor(StyleResolverState&, CSSValue*, bool forVisitedLink = false);
     template <typename T> static T convertComputedLength(StyleResolverState&, CSSValue*);
+    template <typename T> static T convertFlags(StyleResolverState&, CSSValue*);
     static EGlyphOrientation convertGlyphOrientation(StyleResolverState&, CSSValue*);
     static GridPosition convertGridPosition(StyleResolverState&, CSSValue*);
     static GridTrackSize convertGridTrackSize(StyleResolverState&, CSSValue*);
@@ -79,6 +80,15 @@ T StyleBuilderConverter::convertComputedLength(StyleResolverState& state, CSSVal
 }
 
 template <typename T>
+T StyleBuilderConverter::convertFlags(StyleResolverState& state, CSSValue* value)
+{
+    T flags = static_cast<T>(0);
+    for (CSSValueListIterator i(value); i.hasMore(); i.advance())
+        flags |= *toCSSPrimitiveValue(i.value());
+    return flags;
+}
+
+template <typename T>
 T StyleBuilderConverter::convertLineWidth(StyleResolverState& state, CSSValue* value)
 {
     CSSPrimitiveValue* primitiveValue = toCSSPrimitiveValue(value);