Test case for SI-7009.

The next commit fixes the problem itself and it's easier to see
in diff what's being fixed exactly.
SI-7009: `@throws` annotation synthesized incorrectly

The 990b3c7 made `scala.throws` annotation polymorphic but forgot to
adapt compiler code that synthesizes it, e.g. when parsing class files.

The consequence was that we would get non-deterministically either
`scala.throws` or `scala.throws[T]` as a type for synthesized annotation.
The reason is that `Symbol.addAnnotation` would call `tpe` method which
does not initialization of symbol so type parameters list would not be
determined correctly. Only if info of that symbol was forced for other
reason we would get `scala.throws[T]`. That non-deterministic behavior
was observed in sbt's incremental compiler.

Here's list of changes this commit introduces:
  * The `Symbol.addAnnotation` that takes symbol as argument calls
    `typeSymbol` instead of `tpe` for deterministic results
  * Introduce `Symbol.addAnnotation` overload that allows us to pass
    an applied type
  * Change all places where polymorphic annotations are synthesized
    to pass an applied type

Fixes SI-7009.

Review by @adriaanm