Remove unused text encoding quirks.

Source/wtf/text/TextEncodingRegistry.h

Index: Source/wtf/text/TextEncodingRegistry.h
diff --git a/Source/wtf/text/TextEncodingRegistry.h b/Source/wtf/text/TextEncodingRegistry.h
index 74ec4252e49efde6bf19fd20f21964fdc4b7a129..1203b57c017247b581792c23734e77dc415dc1ee 100644
--- a/Source/wtf/text/TextEncodingRegistry.h
+++ b/Source/wtf/text/TextEncodingRegistry.h
@@ -46,8 +46,6 @@ template <typename CharacterType>
 const char* atomicCanonicalTextEncodingName(const CharacterType*, size_t);
 const char* atomicCanonicalTextEncodingName(const String&);
 bool noExtendedTextEncodingNameUsed();
-bool isJapaneseEncoding(const char* canonicalEncodingName);
-bool shouldShowBackslashAsCurrencySymbolIn(const char* canonicalEncodingName);
 bool isReplacementEncoding(const char* alias);
 bool isReplacementEncoding(const String& alias);
 
@@ -60,8 +58,6 @@ void dumpTextEncodingNameMap();
 using WTF::newTextCodec;
 using WTF::atomicCanonicalTextEncodingName;
 using WTF::noExtendedTextEncodingNameUsed;
-using WTF::isJapaneseEncoding;
-using WTF::shouldShowBackslashAsCurrencySymbolIn;
 #ifndef NDEBUG
 using WTF::dumpTextEncodingNameMap;
 #endif