RFR: 8274635: Use String.equals instead of String.compareTo in jdk.accessibility

[Andrey Turbanov]

In several places, String.compareTo was _compared_ with 0 ( via `== 0`).
Instead of this, we can use String.equals calls. `String.equals` is faster and shorter.

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Commit messages:
 - [PATCH] Use String.equals instead of String.compareTo in jdk.accessibility

Changes: https://git.openjdk.java.net/jdk/pull/5752/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5752&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8274635
  Stats: 14 lines in 2 files changed: 0 ins; 2 del; 12 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5752.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5752/head:pull/5752

PR: https://git.openjdk.java.net/jdk/pull/5752