RFR: 8265474: Dubious 'null' assignment in CompactByteArray.expand

[Andrey Turbanov]

I propose to remove 'null' assignment of field CompactByteArray.values in `expand` method. In the next statement this field is overridden with another value - `tempArray`.
This code was there from initial load of OpenJDK sources. I believe it was just leftovers from development phase of this class. There is no practical reason to assign `null` to non-volatile field and then overwrite it with another value.
Also I've removed unused method `getArray`. I hope it's ok to cleanup such unused stuff in the same PR.

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Commit messages:
 - 8265474: Dubious 'null' assignment in CompactByteArray.expand
 - [PATCH] Remove dubious 'null' assignment to CompactByteArray.values

Changes: https://git.openjdk.java.net/jdk/pull/1880/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1880&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8265474
  Stats: 9 lines in 1 file changed: 0 ins; 6 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1880.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1880/head:pull/1880

PR: https://git.openjdk.java.net/jdk/pull/1880