RFR: JDK-8291974 PrivateCredentialPermission should not use local variable to enable debugging [v5]

[Mark Powers]

> https://bugs.openjdk.org/browse/JDK-8291974

Mark Powers has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains seven additional commits since the last revision:

 - Merge
 - implements Serializable
 - Sean comments
 - Text Blocks
 - long line
 - added test
 - first iteration

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/10206/files
  - new: https://git.openjdk.org/jdk/pull/10206/files/b3698128..ce27a083

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10206&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10206&range=03-04

  Stats: 306390 lines in 4313 files changed: 166247 ins; 89978 del; 50165 mod
  Patch: https://git.openjdk.org/jdk/pull/10206.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10206/head:pull/10206

PR: https://git.openjdk.org/jdk/pull/10206