Encoding API: Update tests and simplify constructors

Source/modules/encoding/TextEncoder.cpp

Index: Source/modules/encoding/TextEncoder.cpp
diff --git a/Source/modules/encoding/TextEncoder.cpp b/Source/modules/encoding/TextEncoder.cpp
index 2cfa360b6014cda4cda9300cdb3684d13847cc5b..b1d2be1afa8e37e9920bf1c661c44c5ea636e398 100644
--- a/Source/modules/encoding/TextEncoder.cpp
+++ b/Source/modules/encoding/TextEncoder.cpp
@@ -55,12 +55,12 @@ TextEncoder* TextEncoder::create(const String& utfLabel, ExceptionState& excepti
         return 0;
     }
 
-    return new TextEncoder(encoding.name());
+    return new TextEncoder(encoding);
 }
 
-TextEncoder::TextEncoder(const String& encoding)
+TextEncoder::TextEncoder(const WTF::TextEncoding& encoding)
     : m_encoding(encoding)
-    , m_codec(newTextCodec(m_encoding))
+    , m_codec(newTextCodec(encoding))
 {
 }