RFR: 8274333: Redundant null comparison after Pattern.split

[Andrey Turbanov]

In couple of classes, result part of arrays of Pattern.split is compared with `null`. Pattern.split (and hence String.split) never returns `null` in array elements. Such comparisons are redundant.

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Commit messages:
 - [PATCH] Remove redundant 'null' comparison after Pattern.split

Changes: https://git.openjdk.java.net/jdk/pull/5708/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5708&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8274333
  Stats: 15 lines in 2 files changed: 4 ins; 5 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5708.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5708/head:pull/5708

PR: https://git.openjdk.java.net/jdk/pull/5708