RFR (XS): 8223267: Fix incorrect usage of GCTraceTime in g1FullCollector and g1CollectedHeap

[Kim Barrett]

> On May 2, 2019, at 6:49 PM, Man Cao <manc at google.com> wrote:
> 
> Hi all,
> 
> Can I have reviews for this small bug fix for timer values in the log?
> Webrev: https://cr.openjdk.java.net/~manc/8223267/webrev.00/
> Bug: https://bugs.openjdk.java.net/browse/JDK-8223267
> 
> -Man

Looks good, and trivial.