RFR: 8289397: Fix warnings: Possible accidental assignment in place of a comparison. A condition expression should not be reduced to an assignment

[Andy Goryachev]

- replaced with exact functional equivalent (in the presence of exceptions, for example)

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Commit messages:
 - 8289397: functional equivalent
 - 8289397: fixed possible assignment in place of a comparison warnings

Changes: https://git.openjdk.org/jfx/pull/851/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=851&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8289397
  Stats: 7 lines in 3 files changed: 0 ins; 1 del; 6 mod
  Patch: https://git.openjdk.org/jfx/pull/851.diff
  Fetch: git fetch https://git.openjdk.org/jfx pull/851/head:pull/851

PR: https://git.openjdk.org/jfx/pull/851