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

[Zhiqiang Zang]

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

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Commit messages:
 - format.
 - format whitespace.
 - add some missing tests for existing idealizations.

Changes: https://git.openjdk.org/jdk/pull/11049/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11049&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8297384
  Stats: 582 lines in 11 files changed: 505 ins; 0 del; 77 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