[OpenJDK 2D-Dev] RFR: 8264923: PNGImageWriter.write_zTXt throws Exception with a typo

[Aleksey Shipilev]

Noticed this when backporting JDK-8242557: there is a trivial copy-paste error in exception message. See:
 https://hg.openjdk.java.net/jdk/jdk/rev/645c71334acd#l1.58

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Commit messages:
 - 8264923: PNGImageWriter.write_zTXt throws Exception with a typo

Changes: https://git.openjdk.java.net/jdk/pull/3397/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=3397&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8264923
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3397.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3397/head:pull/3397

PR: https://git.openjdk.java.net/jdk/pull/3397