Proposal: ArrayList constructor perforrmance improvement

[Martin Buchholz]

Sorry for not having remembered the history.
Having ArrayList(Collection) delegate to toArray was done for performance
and robustness.
We don't want to change the "trimming" behavior of collection copying,
because trimming by copying is a common idiom (we never added trimming
methods to all the collection classes).
We seem to be in agreement that we should not change anything here.