The concurrentMark.* files have some stylistic nuisances compared to the rest of G1 and the majority of HotSpot code. In particular, if- and if-else- statements often are missing the curly brackets if the body is a single line. This is in direct violation to what happens in the rest of the HotSpot codebase.
This is a non-essential but simple change but helpful to make those files more consistent with the rest of the codebase.