type annotations are not visible to javac plugins across compilation boundaries

Summary

Update javac's implementation of TypeMirror to allow accessing type use annotations on types loaded from class files.

Problem

The implementation currently does not associate type use annotations loaded from class files with the corresponding types. This means that TypeMirror APIs including getAnnotationMirrors and toString do not accurately report type use annotations for types loaded from class files.

Solution

If a type annotation is present on a type read from a class file, the implementation should associate the annotation with its type.

Specification

No specification change; behavioral change only.