[lworld] RFR: 8281073: [lworld] Update MethodHandles::zero, empty, constant APIs for primitive classes [v2]

[Mandy Chung]

> The `MethodHandles::zero` and `MethodHandles::empty` APIs are updated to return a primitive object with the default value if the given type is a primitive value type. These methods return null if the given type is a value class and a primitive reference type.
> 
> The MethodHandles::constant method will throw `NullPointerException` if the given type is a primitive value type and the given value is null.   That's the same behavior as the `int` type but such case is missing in the spec.

Mandy Chung has updated the pull request incrementally with one additional commit since the last revision:

  fix typo

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

Changes:
  - all: https://git.openjdk.java.net/valhalla/pull/644/files
  - new: https://git.openjdk.java.net/valhalla/pull/644/files/e4d0bbe7..5f353636

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=valhalla&pr=644&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=valhalla&pr=644&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/valhalla/pull/644.diff
  Fetch: git fetch https://git.openjdk.java.net/valhalla pull/644/head:pull/644

PR: https://git.openjdk.java.net/valhalla/pull/644