Summary: Only cosmetic changes to make the concurrentMark.* more consistent, code-style-wise, with the rest of the codebase.
Reviewed-by: johnc, ysr

Summary: Some optimizations to improve the concurrent marking phase: specialize the main oop closure, make sure a few methods in the fast path are properly inlined, a few more bits and pieces, and some cosmetic fixes.
Reviewed-by: stefank, johnc