RFR: 8231779: crash HeapWord*ParallelScavengeHeap::failed_mem_allocate

[Poonam Parhar]

Hello,

Please review this simple change that avoids a double to float 
conversion that would fix an intermittent crash seen on Solaris boxes 
due to corrupted float values in the Floating Point registers.

http://cr.openjdk.java.net/~poonam/8231779/webrev.00/
https://bugs.openjdk.java.net/browse/JDK-8231779

Thanks,
Poonam