Prevent direct use of "replacement" text encoding.

Source/wtf/text/TextEncodingRegistry.cpp

Index: Source/wtf/text/TextEncodingRegistry.cpp
diff --git a/Source/wtf/text/TextEncodingRegistry.cpp b/Source/wtf/text/TextEncodingRegistry.cpp
index 4bbf81b1e99f9a9f7a7b9c673ff7c1e08868d5c8..7c4bd4bce80c9c6c48a9b98f13cd330f7051882c 100644
--- a/Source/wtf/text/TextEncodingRegistry.cpp
+++ b/Source/wtf/text/TextEncodingRegistry.cpp
@@ -269,6 +269,16 @@ bool isJapaneseEncoding(const char* canonicalEncodingName)
     return canonicalEncodingName && japaneseEncodings && japaneseEncodings->contains(canonicalEncodingName);
 }
 
+bool isReplacementEncoding(const char* alias)
+{
+    return alias && !strcasecmp(alias, "replacement");
+}
+
+bool isReplacementEncoding(const String& alias)
+{
+    return alias == "replacement";
+}
+
 bool shouldShowBackslashAsCurrencySymbolIn(const char* canonicalEncodingName)
 {
     return canonicalEncodingName && nonBackslashEncodings && nonBackslashEncodings->contains(canonicalEncodingName);