RFR: JDK-8282776: Bad NullPointerException message when invoking an interface MethodHandle on a null receiver

[Mandy Chung]

A simple patch to call `Objects.requireNonNull(recv)` for an explicit null receiver check rather than NPE thrown by `Object::getClass`.  The message of NPE generated by JEP 358 (Helpful NullPointerExceptions) is supposed to be helpful but not in this case.

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

Commit messages:
 - JDK-8282776: Bad NullPointerException message when invoking an interface MethodHandle on a null receiver

Changes: https://git.openjdk.java.net/jdk/pull/7766/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7766&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8282776
  Stats: 2 lines in 1 file changed: 2 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7766.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7766/head:pull/7766

PR: https://git.openjdk.java.net/jdk/pull/7766