RFR: 8335451: Prototype support for an exact integer arithmetic type

[Joe Darcy]

The Math class has support for "exact" forms of int and long add, subtract, multiply, and divide that throw exceptions instead of wrapping around in a two's complement sense. This nested class in Integer prototype what adding type-level support for that functionality would look like.

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Commit messages:
 - 8335451: Prototype support for an exact integer arithmetic type

Changes: https://git.openjdk.org/valhalla/pull/1937/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1937&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8335451
  Stats: 426 lines in 1 file changed: 425 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/valhalla/pull/1937.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1937/head:pull/1937

PR: https://git.openjdk.org/valhalla/pull/1937