RFR: 8366584: Add an InstanceKlass::super() method that returns InstanceKlass* [v3]

[Ioi Lam]

> By adding an `InstanceKlass* InstanceKlass::super()` method to shadow `Klass* Klass:super()`, this PR makes it possible to simplify the following code
> 
> 
> InstanceKlass* ik;
> InstanceKlass* s;
> s = InstanceKlass::cast(ik->super()); // before JDK-8366024 
> s = ik->java_super(); // after JDK-8366024 
> 
> 
> to
> 
> 
> s = k->super();
> 
> 
> So you no longer need to do casting or need to understand what `java_super()` is.

Ioi Lam has updated the pull request incrementally with one additional commit since the last revision:

  @dholmes-ora and @coleep comments

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/27037/files
  - new: https://git.openjdk.org/jdk/pull/27037/files/e1bac273..dd0a3c5a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27037&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27037&range=01-02

  Stats: 3 lines in 2 files changed: 0 ins; 1 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/27037.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27037/head:pull/27037

PR: https://git.openjdk.org/jdk/pull/27037