Encoding API: Update tests and simplify constructors

Source/modules/encoding/TextDecoder.cpp

Index: Source/modules/encoding/TextDecoder.cpp
diff --git a/Source/modules/encoding/TextDecoder.cpp b/Source/modules/encoding/TextDecoder.cpp
index 84df22cad1c6f5b8fa545d123d5e612747d6da51..dbd1eb3fbd9a7a6ecffab3fc70d1e75620c2acdc 100644
--- a/Source/modules/encoding/TextDecoder.cpp
+++ b/Source/modules/encoding/TextDecoder.cpp
@@ -51,13 +51,13 @@ TextDecoder* TextDecoder::create(const String& label, const Dictionary& options,
     bool fatal = false;
     options.get("fatal", fatal);
 
-    return new TextDecoder(encoding.name(), fatal);
+    return new TextDecoder(encoding, fatal);
 }
 
 
-TextDecoder::TextDecoder(const String& encoding, bool fatal)
+TextDecoder::TextDecoder(const WTF::TextEncoding& encoding, bool fatal)
     : m_encoding(encoding)
-    , m_codec(newTextCodec(m_encoding))
+    , m_codec(newTextCodec(encoding))
     , m_fatal(fatal)
     , m_bomSeen(false)
 {