* Add caching for printing
For printing the last argument expansion, we need to print the same node a bit differently with a flag. It's not easy to re-print just the node that is different so we end up printing all the sub-tree twice. Since it is often nested, it means that we run into an exponential complexity.
I finally found a simple solution: we can use a Map to store the nodes and their printed values. It is really cheap to do so (I can't notice a time difference with or without on normal code) and allows us to stop going through the two sub-trees in the bad case.
Fixes#1250
* Update printer.js