MethodHandles: fix missing check in VarHandle invoker

Fixes missing UnsupportedOperationException check when a VarHandle is
invoked via a MethodHandle.

Bug: 207844518
Test: art/test/run-test --host 713
Change-Id: I8152e6bfdf0d86cfc17fff64edc6df5160b0f8fd
2 files changed