upgrade review.o.o to gerrit ver 2.8.4

this change is to upgrade gerrit on review.o.o.  The equivalent change to
upgrade review-dev.o.o is in change I8dede1f7a413ebc0e53a092c34b7e87f78f41f9b

Change-Id: Ia01641b0972030dd37eb75c7c894dd70785221a6
Merge "upgrade review.o.o to gerrit ver 2.8.4"