RFR (trivial) 8189794: Assert in InstanceKlass::cast called from Exceptions::new_exceptions

[coleen.phillimore at oracle.com]

Thank you Serguei and David.
Coleen

On 10/23/17 9:57 PM, serguei.spitsyn at oracle.com wrote:
> Hi Coleen,
>
> Looks good.
>
> Thanks,
> Serguei
>
>
> On 10/23/17 15:29, coleen.phillimore at oracle.com wrote:
>> Summary: Fix call to InstanceKlass::cast to only be after verifying 
>> class is non-null.
>>
>> Also fixed an unnecessary InstanceKlass::cast found while looking for 
>> similar instances of this bug.  I didn't find this same bug anywhere 
>> else.  Tested with internal vm.gc.locker tests, and with JPRT which 
>> is equivalent to tier1 only faster at the moment.
>>
>> open webrev at http://cr.openjdk.java.net/~coleenp/8189794.01/webrev
>> bug link https://bugs.openjdk.java.net/browse/JDK-8189794
>>
>> Thanks,
>> Coleen
>