RFR: 8258593: remove redundant codes in HeapObjectDumper

[Lin Zang]

8258593: remove redundant codes in HeapObjectDumper

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Commit messages:
 - 8258593: remove redundant codes in HeapObjectDumper

Changes: https://git.openjdk.java.net/jdk/pull/1819/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1819&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8258593
  Stats: 5 lines in 1 file changed: 0 ins; 3 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1819.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1819/head:pull/1819

PR: https://git.openjdk.java.net/jdk/pull/1819