Remove dart backend

test/dart_codegen/expect/convert/encoding.dart

-part of dart.convert;
- abstract class Encoding extends Codec<String, List<int>> {const Encoding();
- Future<String> decodeStream(Stream<List<int>> byteStream) {
-  return ((__x3) => DEVC$RT.cast(__x3, DEVC$RT.type((DDC$async$.Future<dynamic> _) {
-    }
-  ), DEVC$RT.type((DDC$async$.Future<String> _) {
-    }
-  ), "CompositeCast", """line 14, column 12 of dart:convert/encoding.dart: """, __x3 is DDC$async$.Future<String>, false))(byteStream.transform(decoder).fold(new StringBuffer(), (buffer, string) => buffer..write(string)).then((buffer) => buffer.toString()));
-  }
- String get name;
- static Map<String, Encoding> _nameToEncoding = <String, Encoding> {
-  "iso_8859-1:1987" : LATIN1, "iso-ir-100" : LATIN1, "iso_8859-1" : LATIN1, "iso-8859-1" : LATIN1, "latin1" : LATIN1, "l1" : LATIN1, "ibm819" : LATIN1, "cp819" : LATIN1, "csisolatin1" : LATIN1, "iso-ir-6" : ASCII, "ansi_x3.4-1968" : ASCII, "ansi_x3.4-1986" : ASCII, "iso_646.irv:1991" : ASCII, "iso646-us" : ASCII, "us-ascii" : ASCII, "us" : ASCII, "ibm367" : ASCII, "cp367" : ASCII, "csascii" : ASCII, "ascii" : ASCII, "csutf8" : UTF8, "utf-8" : UTF8}
-;
- static Encoding getByName(String name) {
-  if (name == null) return null;
-   name = name.toLowerCase();
-   return _nameToEncoding[name];
-  }
-}