RFR: 8273369: Computing micros between two instants unexpectedly overflows for some cases [v6]

[Naoto Sato]

> Please review the fix to the issue. Avoiding overflow by not calling nanosUntil() directly, which will overflow beyond Long.MAX_VALUE difference in nano unit.

Naoto Sato has updated the pull request incrementally with one additional commit since the last revision:

  Corrected the calculation for MILLIS as well.

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/5396/files
  - new: https://git.openjdk.java.net/jdk/pull/5396/files/ccf73bf7..1f6fd470

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=5396&range=05
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=5396&range=04-05

  Stats: 24 lines in 3 files changed: 21 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5396.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5396/head:pull/5396

PR: https://git.openjdk.java.net/jdk/pull/5396