Chrome Version: 55.0.2883.87 

In theory, the result of the < comparison of the underlying pointers at 
https://cs.chromium.org/chromium/src/base/memory/ref_counted.h?rcl=0&l=381
is unspecified if the two pointers don't point within the same "object" (e.g. same segment on a long-dead segmented architecture).

Currently, this doesn't affect anything, but if we want strict correctness, the std::less<>() method provides a total ordering even in light of the above limitation.