[code-reflection] RFR: Add common supertype for type-variable owners [v2]

[Maurizio Cimadamore]

> This is a followup of https://git.openjdk.org/babylon/pull/64
> 
> The goal is to define a common supertype for type-variable owner, namely `Type>
> 
> This is a sealed interface implemented by both `MethodRef` and `ClassType`.

Maurizio Cimadamore has updated the pull request incrementally with one additional commit since the last revision:

  Address review comments

-------------

Changes:
  - all: https://git.openjdk.org/babylon/pull/66/files
  - new: https://git.openjdk.org/babylon/pull/66/files/b666cce2..683410cd

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=babylon&pr=66&range=01
 - incr: https://webrevs.openjdk.org/?repo=babylon&pr=66&range=00-01

  Stats: 14 lines in 1 file changed: 0 ins; 11 del; 3 mod
  Patch: https://git.openjdk.org/babylon/pull/66.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/66/head:pull/66

PR: https://git.openjdk.org/babylon/pull/66