RFR: JDK-8272192 Shortcut String equality checks by checking equality of the value array

[q2q-2q2]

Shortcut String equality checks by checking equality of the value array

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Commit messages:
 - JDK-8272192

Changes: https://git.openjdk.java.net/jdk/pull/5370/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5370&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8272192
  Stats: 62 lines in 3 files changed: 60 ins; 1 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5370.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5370/head:pull/5370

PR: https://git.openjdk.java.net/jdk/pull/5370