- Cleaned up some comments
- Removed the "is power of two" check from optimizedCapacity since the * 5 / 3 is unlikely to end up with a power of two, so it's a wasted check the majority of the time
- Made ensureCapacity/ensureCapacityExact increment the modification count if they resize the hash map so that we can catch resizes while iterating, which would likely break the iterator state