Refactoring: Use enum class for SerializationType

Source/core/xml/XMLSerializer.cpp

Index: Source/core/xml/XMLSerializer.cpp
diff --git a/Source/core/xml/XMLSerializer.cpp b/Source/core/xml/XMLSerializer.cpp
index 52d47621d28da8f9cfc9eeafb232942ce4c3de4f..c3b8d4d8a11a20181bb8e7f2a488d13fd1c54da9 100644
--- a/Source/core/xml/XMLSerializer.cpp
+++ b/Source/core/xml/XMLSerializer.cpp
@@ -29,7 +29,7 @@ namespace blink {
 String XMLSerializer::serializeToString(Node* root)
 {
     ASSERT(root);
-    MarkupAccumulator accumulator(DoNotResolveURLs, ForcedXML);
+    MarkupAccumulator accumulator(DoNotResolveURLs, SerializationType::ForcedXML);
     return serializeNodes<EditingStrategy>(accumulator, *root, IncludeNode);
 }