dartc has broken type checking in some cases

[DartBot]

This issue was originally filed by zundel@google.com

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In checked mode (dartc --enable_type_checks), there is a bug in runtime type checking in some cases. Here's a test that exercises it

TypeChecksInFactoryMethods.dart

interface Foo<T> default Bar {
  Foo.from();
}

class Bar<T> implements Foo<T> {
  Bar() {}

  factory Bar.from() {
    var func = (T arg) { print(arg); }; // If T is not a string, runtime checks should fail
    func("Hello World!");
    return new Bar<T>();
  }
}

main() {
  Foo value;
  value = new Foo<String>.from();

  bool gotError = false;

  try {
    value = new Foo<int>.from();
  } catch (TypeError e) {
    gotError = true;
  }
  Expect.equals(true, gotError);
}

Basically, getting type arguments into the hoisted methods from a factory method hasn't been worked out. Factory methods get their type arguments passed in as the first parameter, for other methods, the arguments are passed on a property of 'this' but in these hoisted methods from a factory, 'this' is set to Dart$Null.

[scheglov]

We are removing code generation from DartC.

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Added WontFix label.