RFR: 8149128: Add tests for G1MMUTracker

[Kim Barrett]

> On Jun 17, 2016, at 6:15 AM, Erik Helin <erik.helin at oracle.com> wrote:
> - incremental: http://cr.openjdk.java.net/~ehelin/8149128/00-01/webrev/
> - full: http://cr.openjdk.java.net/~ehelin/8149128/01/webrev/

Looks good.

>> ----------------------------------------------------------------------------- 
>> The following (convenience) functions are untested.
>> when_max_gc_sec
>> when_max_gc_ms
>> when_ms
> 
> I plan to remove most of these, since they are barely used. For now I
> would like to not test them.

OK.