When calculating a value to see if we can do a type of comparison, store
that value so we don't have to calculate it again. Use Try*Evaluate
instead of Can*Evaluate and *Evaluate.

Removes all *Evaluate and Can*Evaluate except in OperatorExpressionNodes, for which CanBoolEvaluate always returns true, so using a simple BoolEvaluate makes sense.

Note that for the NumericComparisonExpressionNode, we could save a tiny amount of time by only calling TryEvaluate when it's actually used (and using if/else as before), but that would since something can be both a number and a version, that would mean we would have to check both regardless of what we had previously found, which means it would be noticeably messier for (probably) very little perf gain, so I opted against that. Switch statements are so pretty 🙂

Apparently that's the best supported way

I tested once with and once without this change, and with this change, Evaluate was 3% faster...that sounds noisy, but I'll still take it.