SI-1786 incorporate defined bounds in inference

Also fixes SI-5459.

Look, you don't have to redeclare the bounds, isn't it exciting? For instance,
there are eight places in JavaMirrors with this:

  jTypeVariable[_ <: GenericDeclaration]

After this code is in starr, those can look like this:

  jTypeVariable[_]

Since TypeVariable's definition looks like this:

  interface TypeVariable<D extends GenericDeclaration>

We already know that!