Typecheck constructor initializers properly

test/codegen/expect/core/core.js

 var core;
 (function(core) {
   'use strict';
   // Function _symbolToString: (Symbol) → String
   function _symbolToString(symbol) {
     return _internal.Symbol.getName(dart.as(symbol, _internal.Symbol));
   }
   // Function _symbolMapToStringMap: (Map<Symbol, dynamic>) → dynamic
   function _symbolMapToStringMap(map) {
     if (map === null)
@@ skipping 237 matching lines @@
     subtract(duration) {
       let ms = this.millisecondsSinceEpoch;
       return new DateTime.fromMillisecondsSinceEpoch(ms - duration.inMilliseconds, {isUtc: this.isUtc});
     }
     difference(other) {
       let ms = this.millisecondsSinceEpoch;
       let otherMs = other.millisecondsSinceEpoch;
       return new Duration({milliseconds: ms - otherMs});
     }
     DateTime$_internal(year, month, day, hour, minute, second, millisecond, isUtc) {
-      this.isUtc = typeof isUtc == boolean ? isUtc : dart.throw_(new ArgumentError(isUtc));
-      this.millisecondsSinceEpoch = dart.dinvokef(/* Unimplemented unknown name */checkInt, dart.dinvoke(/* Unimplemented unknown name */Primitives, 'valueFromDecomposedDate', year, month, day, hour, minute, second, millisecond, isUtc));
+      this.isUtc = dart.as(typeof isUtc == boolean ? isUtc : dart.throw_(new ArgumentError(isUtc)), bool);
+      this.millisecondsSinceEpoch = dart.as(dart.dinvokef(/* Unimplemented unknown name */checkInt, dart.dinvoke(/* Unimplemented unknown name */Primitives, 'valueFromDecomposedDate', year, month, day, hour, minute, second, millisecond, isUtc)), int);
     }
     DateTime$_now() {
       this.isUtc = false;
-      this.millisecondsSinceEpoch = dart.dinvoke(/* Unimplemented unknown name */Primitives, 'dateNow');
+      this.millisecondsSinceEpoch = dart.as(dart.dinvoke(/* Unimplemented unknown name */Primitives, 'dateNow'), int);
     }
     static _brokenDownDateToMillisecondsSinceEpoch(year, month, day, hour, minute, second, millisecond, isUtc) {
       return dart.as(dart.dinvoke(/* Unimplemented unknown name */Primitives, 'valueFromDecomposedDate', year, month, day, hour, minute, second, millisecond, isUtc), int);
     }
     get timeZoneName() {
       if (this.isUtc)
         return "UTC";
       return dart.as(dart.dinvoke(/* Unimplemented unknown name */Primitives, 'getTimeZoneName', this), String);
     }
     get timeZoneOffset() {
@@ skipping 368 matching lines @@
   dart.defineNamedConstructor(RangeError, 'index');
   class IndexError extends ArgumentError {
     IndexError(invalidValue, indexable, name, message, length) {
       if (name === void 0)
         name = null;
       if (message === void 0)
         message = null;
       if (length === void 0)
         length = null;
       this.indexable = indexable;
-      this.length = length !== null ? length : dart.dload(indexable, 'length');
+      this.length = dart.as(length !== null ? length : dart.dload(indexable, 'length'), int);
       super.ArgumentError$value(invalidValue, name, message !== null ? message : "Index out of range");
     }
     get start() {
       return 0;
     }
     get end() {
       return this.length - 1;
     }
     toString() {
       dart.assert(this._hasValue);
@@ skipping 362 matching lines @@
     }
     dart.defineNamedConstructor(Iterable, 'generate');
     return Iterable;
   });
   let Iterable = Iterable$(dynamic);
   let _GeneratorIterable$ = dart.generic(function(E) {
     class _GeneratorIterable extends collection.IterableBase$(E) {
       _GeneratorIterable(_end, generator) {
         this._end = _end;
         this._start = 0;
-        this._generator = generator !== null ? generator : _id;
+        this._generator = dart.as(generator !== null ? generator : _id, _Generator);
         super.IterableBase();
       }
       _GeneratorIterable$slice(_start, _end, _generator) {
         this._start = _start;
         this._end = _end;
         this._generator = _generator;
         super.IterableBase();
       }
       get iterator() {
         return new _GeneratorIterator(this._start, this._end, this._generator);
@@ skipping 1902 matching lines @@
   core.Stopwatch = Stopwatch;
   core.String = String;
   core.Runes = Runes;
   core.RuneIterator = RuneIterator;
   core.StringBuffer = StringBuffer;
   core.StringSink = StringSink;
   core.Symbol = Symbol;
   core.Type = Type;
   core.Uri = Uri;
 })(core || (core = {}));