Typecheck constructor initializers properly

test/dart_codegen/expect/convert/utf.dart

 part of dart.convert;
  const int UNICODE_REPLACEMENT_CHARACTER_RUNE = 0xFFFD;
  const int UNICODE_BOM_CHARACTER_RUNE = 0xFEFF;
  const Utf8Codec UTF8 = const Utf8Codec();
  class Utf8Codec extends Encoding {final bool _allowMalformed;
  const Utf8Codec({
   bool allowMalformed : false}
 ) : _allowMalformed = allowMalformed;
  String get name => "utf-8";
  String decode(List<int> codeUnits, {
@@ skipping 19 matching lines @@
  assert (endPosition >= end - 1); if (endPosition != end) {
   int lastCodeUnit = string.codeUnitAt(end - 1);
    assert (_isLeadSurrogate(lastCodeUnit)); bool wasCombined = encoder._writeSurrogate(lastCodeUnit, 0);
    assert (!wasCombined);}
  return encoder._buffer.sublist(0, encoder._bufferIndex);
 }
  StringConversionSink startChunkedConversion(Sink<List<int>> sink) {
 if (sink is! ByteConversionSink) {
   sink = new ByteConversionSink.from(sink);
   }
- return new _Utf8EncoderSink(sink);
+ return new _Utf8EncoderSink(DDC$RT.cast(sink, DDC$RT.type((Sink<List<int>> _) {
+  }
+), ByteConversionSink, "CastGeneral", """line 125, column 33 of dart:convert/utf.dart: """, sink is ByteConversionSink, true));
 }
- Stream<List<int>> bind(Stream<String> stream) => ((__x30) => DDC$RT.cast(__x30, DDC$RT.type((DDC$async$.Stream<dynamic> _) {
+ Stream<List<int>> bind(Stream<String> stream) => ((__x33) => DDC$RT.cast(__x33, DDC$RT.type((DDC$async$.Stream<dynamic> _) {
 }
 ), DDC$RT.type((DDC$async$.Stream<List<int>> _) {
 }
-), "CastDynamic", """line 129, column 52 of dart:convert/utf.dart: """, __x30 is DDC$async$.Stream<List<int>>, false))(super.bind(stream));
+), "CastDynamic", """line 129, column 52 of dart:convert/utf.dart: """, __x33 is DDC$async$.Stream<List<int>>, false))(super.bind(stream));
 }
  class _Utf8Encoder {int _carry = 0;
  int _bufferIndex = 0;
  final List<int> _buffer;
  static const _DEFAULT_BYTE_BUFFER_SIZE = 1024;
  _Utf8Encoder() : this.withBufferSize(DDC$RT.cast(_DEFAULT_BYTE_BUFFER_SIZE, dynamic, int, "CastGeneral", """line 143, column 40 of dart:convert/utf.dart: """, _DEFAULT_BYTE_BUFFER_SIZE is int, true));
  _Utf8Encoder.withBufferSize(int bufferSize) : _buffer = _createBuffer(bufferSize);
  static List<int> _createBuffer(int size) => new Uint8List(size);
  bool _writeSurrogate(int leadingSurrogate, int nextCodeUnit) {
 if (_isTailSurrogate(nextCodeUnit)) {
@@ skipping 104 matching lines @@
  ByteConversionSink startChunkedConversion(Sink<String> sink) {
 StringConversionSink stringSink;
  if (sink is StringConversionSink) {
 stringSink = sink;
 }
  else {
 stringSink = new StringConversionSink.from(sink);
 }
  return stringSink.asUtf8Sink(_allowMalformed);
 }
- Stream<String> bind(Stream<List<int>> stream) => ((__x31) => DDC$RT.cast(__x31, DDC$RT.type((DDC$async$.Stream<dynamic> _) {
+ Stream<String> bind(Stream<List<int>> stream) => ((__x34) => DDC$RT.cast(__x34, DDC$RT.type((DDC$async$.Stream<dynamic> _) {
 }
 ), DDC$RT.type((DDC$async$.Stream<String> _) {
 }
-), "CastDynamic", """line 361, column 52 of dart:convert/utf.dart: """, __x31 is DDC$async$.Stream<String>, false))(super.bind(stream));
+), "CastDynamic", """line 361, column 52 of dart:convert/utf.dart: """, __x34 is DDC$async$.Stream<String>, false))(super.bind(stream));
  external Converter<List<int>, dynamic> fuse(Converter<String, dynamic> next);
 }
  const int _ONE_BYTE_LIMIT = 0x7f;
  const int _TWO_BYTE_LIMIT = 0x7ff;
  const int _THREE_BYTE_LIMIT = 0xffff;
  const int _FOUR_BYTE_LIMIT = 0x10ffff;
  const int _SURROGATE_MASK = 0xF800;
  const int _SURROGATE_TAG_MASK = 0xFC00;
  const int _SURROGATE_VALUE_MASK = 0x3FF;
  const int _LEAD_SURROGATE_MIN = 0xD800;
@@ skipping 127 matching lines @@
 }
  break loop;
 }
  if (expectedUnits > 0) {
 _value = value;
  _expectedUnits = expectedUnits;
  _extraUnits = extraUnits;
 }
 }
 }