Typecheck constructor initializers properly

test/dart_codegen/expect/convert/json.dart

 part of dart.convert;
  class JsonUnsupportedObjectError extends Error {final unsupportedObject;
  final cause;
  JsonUnsupportedObjectError(this.unsupportedObject, {
   this.cause}
 );
  String toString() {
   if (cause != null) {
     return "Converting object to an encodable object failed.";
     }
@@ skipping 196 matching lines @@
  static const int CHAR_0 = 0x30;
  static const int BACKSLASH = 0x5c;
  static const int CHAR_b = 0x62;
  static const int CHAR_f = 0x66;
  static const int CHAR_n = 0x6e;
  static const int CHAR_r = 0x72;
  static const int CHAR_t = 0x74;
  static const int CHAR_u = 0x75;
  final List _seen = new List();
  final Function _toEncodable;
- _JsonStringifier(Object _toEncodable(Object o)) : _toEncodable = (_toEncodable != null) ? _toEncodable : _defaultToEncodable;
+ _JsonStringifier(Object _toEncodable(Object o)) : _toEncodable = ((__x15) => DDC$RT.cast(__x15, dynamic, Function, "CastGeneral", """line 547, column 24 of dart:convert/json.dart: """, __x15 is Function, true))((_toEncodable != null) ? _toEncodable : _defaultToEncodable);
  void writeString(String characters);
  void writeStringSlice(String characters, int start, int end);
  void writeCharCode(int charCode);
  void writeNumber(num number);
  static int hexDigit(int x) => x < 10 ? 48 + x : 87 + x;
  void writeStringContent(String s) {
 int offset = 0;
  final int length = s.length;
  for (int i = 0;
  i < length;
@@ skipping 158 matching lines @@
 }
 }
  void writeMap(Map map) {
 if (map.isEmpty) {
 writeString('{}');
 }
  else {
 writeString('{\n');
  _indentLevel++;
  bool first = true;
- map.forEach(((__x23) => DDC$RT.wrap((dynamic f(String __u15, Object __u16)) {
+ map.forEach(((__x24) => DDC$RT.wrap((dynamic f(String __u16, Object __u17)) {
 dynamic c(String x0, Object x1) => f(DDC$RT.cast(x0, dynamic, String, "CastParam", """line 773, column 19 of dart:convert/json.dart: """, x0 is String, true), x1);
  return f == null ? null : c;
 }
-, __x23, __t20, __t17, "WrapLiteral", """line 773, column 19 of dart:convert/json.dart: """, __x23 is __t17))((String key, Object value) {
+, __x24, __t21, __t18, "WrapLiteral", """line 773, column 19 of dart:convert/json.dart: """, __x24 is __t18))((String key, Object value) {
 if (!first) {
 writeString(",\n");
 }
  writeIndentation(_indentLevel);
  writeString('"');
  writeStringContent(key);
  writeString('": ');
  writeObject(value);
  first = false;
 }
 ));
  writeString('\n');
  _indentLevel--;
  writeIndentation(_indentLevel);
  writeString('}');
 }
 }
 }
  class _JsonStringStringifier extends _JsonStringifier {final StringSink _sink;
- _JsonStringStringifier(this._sink, _toEncodable) : super(DDC$RT.cast(_toEncodable, dynamic, __t24, "CastGeneral", """line 798, column 60 of dart:convert/json.dart: """, _toEncodable is __t24, false));
+ _JsonStringStringifier(this._sink, _toEncodable) : super(DDC$RT.cast(_toEncodable, dynamic, __t25, "CastGeneral", """line 798, column 60 of dart:convert/json.dart: """, _toEncodable is __t25, false));
  static String stringify(object, toEncodable(object), String indent) {
 StringBuffer output = new StringBuffer();
  printOn(object, output, toEncodable, indent);
  return output.toString();
 }
  static void printOn(object, StringSink output, toEncodable(object), String indent) {
 var stringifier;
  if (indent == null) {
 stringifier = new _JsonStringStringifier(output, toEncodable);
 }
@@ skipping 20 matching lines @@
  void writeIndentation(int count) {
 for (int i = 0;
  i < count;
  i++) writeString(_indent);
 }
 }
  class _JsonUtf8Stringifier extends _JsonStringifier {final int bufferSize;
  final Function addChunk;
  Uint8List buffer;
  int index = 0;
- _JsonUtf8Stringifier(toEncodable, int bufferSize, this.addChunk) : super(DDC$RT.cast(toEncodable, dynamic, __t24, "CastGeneral", """line 874, column 15 of dart:convert/json.dart: """, toEncodable is __t24, false)), this.bufferSize = bufferSize, buffer = new Uint8List(bufferSize);
+ _JsonUtf8Stringifier(toEncodable, int bufferSize, this.addChunk) : super(DDC$RT.cast(toEncodable, dynamic, __t25, "CastGeneral", """line 874, column 15 of dart:convert/json.dart: """, toEncodable is __t25, false)), this.bufferSize = bufferSize, buffer = new Uint8List(bufferSize);
  static void stringify(Object object, List<int> indent, toEncodableFunction(Object o), int bufferSize, void addChunk(Uint8List chunk, int start, int end)) {
 _JsonUtf8Stringifier stringifier;
  if (indent != null) {
 stringifier = new _JsonUtf8StringifierPretty(toEncodableFunction, indent, bufferSize, addChunk);
 }
  else {
 stringifier = new _JsonUtf8Stringifier(toEncodableFunction, bufferSize, addChunk);
 }
  stringifier.writeObject(object);
  stringifier.flush();
@@ skipping 98 matching lines @@
  i < indentLength;
  i++) {
 writeByte(indent[i]);
 }
 }
 }
 }
 }
  typedef dynamic __t7(dynamic __u8);
  typedef dynamic __t11(Object __u12);
- typedef void __t17(dynamic __u18, dynamic __u19);
- typedef dynamic __t20(String __u21, Object __u22);
- typedef Object __t24(Object __u25);
+ typedef void __t18(dynamic __u19, dynamic __u20);
+ typedef dynamic __t21(String __u22, Object __u23);
+ typedef Object __t25(Object __u26);