RFR: 8189390: Assert in TestOptionsWithRanges.java

[Roman Kennke]

Apperently I yanked some error handling when extracting the CMSHeap 
class from GenCollectedHeap, which makes TestOptionsWithRanges test fail.

This puts the error handling back in exactly as it was before, which 
makes the test happy:

http://cr.openjdk.java.net/~rkennke/8189390/webrev.00/ 
<http://cr.openjdk.java.net/%7Erkennke/8189390/webrev.00/>

Ok?

Roman