8140583: Without PrintPLAB, there are superfluous newlines in the GC log messages Summary: Conditionalize offending newlines by -XX:+PrintPLAB Reviewed-by: mgerdin

8139116: Fixes for warning "format not a string literal" Reviewed-by: ddmitriev, david, simonis

Merge

8139163: InstanceKlass::cast passes through NULL Summary: Reduce raw (InstanceKlass*) casts and InstanceKlass::cast, which no long allows null Reviewed-by: twisti, kbarrett