RFR: 8297384: Add IR tests for existing idealizations of arithmetic nodes [v2]

[Zhiqiang Zang]

> I noticed some idealizations have no associated IR tests so I included for them.

Zhiqiang Zang has updated the pull request incrementally with one additional commit since the last revision:

  include @bug and @summary for newly created ir test classes.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/11049/files
  - new: https://git.openjdk.org/jdk/pull/11049/files/6930c908..c0931397

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=11049&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=11049&range=00-01

  Stats: 12 lines in 6 files changed: 12 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/11049.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11049/head:pull/11049

PR: https://git.openjdk.org/jdk/pull/11049