RFR 8160439: Replace asserts in VarHandle.AccessMode with tests

[Paul Sandoz]

> On 28 Jun 2016, at 21:37, Martin Buchholz <martinrb at google.com> wrote:
> 
> Looks good.
> 

Thanks.


> I'm still nervous about using assert in performance critical code due to hotspot bytecode count inlining heuristics.
> 

The assert i left in place (because it is asserting on internal data) and the one what was removed were not on the critical performance path. Stil, I learned a lesson to be careful using asserts with code that is used early in the startup process.

Paul.