VM crash in interaction of factories and parametrized types

[ghost]

./vm/ast.h:1663: error: expected: type_arguments_.IsNull() || (type_arguments_.Length() == Class::Handle(constructor_.owner()).NumTypeArguments())

tests/language/src/FactoryGenericsTest.dart

interface Link<T> factory LinkFactory {
  Link.fromInt(int x);
}

class MyLink<T> implements Link<T> {
}

class LinkFactory {
  factory Link.fromInt(int x) {
    return new MyLink();
  }
}

main() {
  var a = new Link<int>.fromInt(2);
}

[ghost]

Added Duplicate label.
Marked as being merged into #226.