Correctly substitue poly qualifier from type argument bounds

[Ao-senXiong]

Fixes #1074

[Ao-senXiong]

OK, the CI reproduce the crash.

[Ao-senXiong]

@wmdietl
For this code,

class MyCollection<E> { 
  void copyOf(MyCollection<? extends E> elements) {
    Object[] array = elements.toArray();
  }
  @PolyVP Object [] toArray(MyCollection<@PolyVP E> this) {
      return null;
  };
}

Currently, @PolyVP E as a type argument is applying polymorphic qualifier to both bounds, i.e. @PolyVP void as lower bound and @PolyVP Object as upper bound. However, elements is using @Bottom void as lower bound and @Top Object as upper bound. There is a mismatch in polymorphic qualifier substitution as in type argument we can not specify lower and upper bound seperately. We need to neither reject the code or use one bound conservatively e.g. replace both bounds to @Top.

Do you have better idea on how to solve this problem?