RFR: 8350097: Make Compilation::current() and Compile::current() safer [v2]

[Thomas Stuefe]

> Somewhat trivial.
> 
> I recently hunted a bug for an hour until I realized that I had accessed ciEnv::compiler_data() as C2 `Compile` when, in fact, it was C1 `Compilation`. Stupid mistake, but an assert is easy to do and saves time.

Thomas Stuefe has updated the pull request incrementally with two additional commits since the last revision:

 - redo
 - Revert "start"
   
   This reverts commit e370e14abf2ee25019ed13cde9edfa24047d982d.

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/23635/files
  - new: https://git.openjdk.org/jdk/pull/23635/files/a103b455..b4b1bbd3

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=23635&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=23635&range=00-01

  Stats: 52 lines in 6 files changed: 21 ins; 23 del; 8 mod
  Patch: https://git.openjdk.org/jdk/pull/23635.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23635/head:pull/23635

PR: https://git.openjdk.org/jdk/pull/23635